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What is MariaDB?

MariaDB is a fork of the MySQL database management system. It is created by its original developers. This DBMS tool offers data processing capabilities for both small and enterprise tasks.

MariaDB is an improved version of MySQL. It comes with numerous inbuilt powerful features and many usabilities, security and performance improvements that you cannot find in MySQL.

Here are the features of MariaDB:

It operates under GPL, BSD or LGPL licenses.

MariaDB supports a popular and standard querying language.

It comes with many storage engines, including the high-performance ones that can be integrated with other relational database management systems.

It provides the Galera cluster technology.

MariaDB supports PHP, a popular language for web development.

MariaDB can run on different operating systems, and it supports numerous programming languages.

MariaDB comes with additional commands that are not available in MySQL. MySQL has features which have a negative impact on the performance of the DBMS. Such features have been replaced in MariaDB.

In this MariaDB tutorial, you will learn:

MariaDB vs. MySQL

Below are some key differences between MariaDB vs MySQL

Parameter MariaDB MySQL

More Options for Storage Engines MariaDB has 12 new storage engines that you won’t find in MySQL. It has fewer options for storage compared to MariaDB.

Speed Improvements MariaDB shows an improved speed when compared to MySQL. It comes with numerous features for optimizing speed. Such features include derived views/tables, subquery, execution control, disk access, and optimizer control. MySQL exhibits a slower speed when compared to MariaDB. It relies on only a few features for speed optimization, for example, hash indexes.

Faster cache/indexes With the Memory storage engine of MariaDB, an INSERT statement can be completed 24% than in the standard MySQL. The memory storage engine of MySQL is slower compared to that MariaDB.

Larger and Faster Connection Pool The thread pool provided by MySQL cannot support up to 200,000 connections per time.

Improved Replication In MariaDB, replication can be done safer and faster. Updates can also be done 2x faster compared to the traditional MySQL.

New Features/Extensions MariaDB comes with new features and extensions including the JSON, WITH and KILL statements. The new MariaDB features are not provided in MySQL.

Missing Features MariaDB lacks some of the features provided by the MySQL enterprise edition. To address this, it offers alternative open-source plugins. Hence, MariaDB users are able to enjoy the same functionalities as MySQL Enterprise Edition users. The Enterprise Edition of MySQL uses a proprietary code. Only users of MySQL Enterprise Edition have access to this.

How to install MariaDB Install as a Standalone Application

In order to use MariaDB, you have to install it on your computer.

The installation can be done by following the steps given below:

Once the download is complete, Open File

In the next window, you will be required to change the password for the root user.

Enter the password and confirm it by retyping the same password. If you want to permit access from remote machines, activate the necessary checkbox.

A progress bar showing the progress of the installation will be shown:

You now have MariaDB installed on your computer.

Working with Command Prompt

Now that you have MariaDB installed on your computer, it is time for you to launch it and begin to use it. This can be done via the MariaDB command prompt.

Follow the steps given below:

Step 2) Choose a MariaDB Command Prompt.

Step 3) The MariaDB command prompt will be started. It is now time to login. You should login as the root user and the password that you set during the installation of MariaDB. Type the following command on the command prompt:

MySQL -u root -p

Step 4) Enter the password and hit the return key. You should be logged in, as shown below:

You are now logged into MariaDB.

Data Types

MariaDB supports the following data types:

String data types

Numeric data types

Date/time data types

Large object data types

String Data Types

These include the following:

String Data Type Description

char(size) The size denotes the number of characters to be stored. It stores a maximum of 255 characters. Fixed-length strings.

varchar(size) The size denotes the number of characters to be stored. It stores a maximum of 255 characters. Variable-length strings.

text(size) The size denotes the number of characters to be stored. It stores a maximum of 255 characters. Fixed-length strings.

binary(size) The size denotes the number of characters to be stored. It stores a maximum of 255 characters. Fixed-size strings.

Numeric Data Types

They include the following:

Numeric Data Types Description

bit A very small integer value equivalent to tinyint(1). Signed values range between -128 and 127. Unsigned values range between 0 and 255.

int(m) A standard integer value. Signed values range between -2147483648 and 2147483647. Unsigned values range between 0 and 4294967295.

float(m, d) A floating point number with single precision.

double(m,d) A floating point number with double precision.

float(p) A floating point number.

Date/Time Data Types

These include the following:

Date/Time Data Type Description

Date Displayed in the form ‘yyyy-mm-dd.’ Values range between ‘1000-01-01’ and ‘9999-12-31’.

Datetime Displayed in the form ‘yyyy-mm-dd hh:mm:ss’. Values range between ‘1000-01-01 00:00:00’ and ‘9999-12-31 23:59:59’.

timestamp(m) Displayed in the form ‘yyyy-mm-dd hh:mm:ss’. Values range between ‘1970-01-01 00:00:01’ utc and ‘2038-01-19 03:14:07’ utc.

Time Displayed in the form ‘hh:mm:ss’. Values range between ‘-838:59:59’ and ‘838:59:59’.

Large Object Datatypes (LOB)

They include the following:

Large object Datatype Description

tinyblob Its maximum size is 255 bytes.

blob(size) Takes 65,535 bytes as the maximum size.

mediumblob Its maximum size is 16,777,215 bytes.

longtext It takes 4GB as the maximum size.

Create a Database and Tables

To create a new database in MariaDB, you should have special privileges which are only granted to the root user and admins.

To create a new database, you should use the CREATE DATABASE command which takes the following syntax:

CREATE DATABASE DatabaseName;

In this case, you need to create a database and give it the name Demo.

Start the MariaDB command prompt and login as the root user by typing the following command:

mysql -u root -p

Type the root password and hit the return key. You will be logged in.

Now, run the following command:

CREATE DATABASE Demo;

You have then created a database named Demo. It will be good for you to confirm whether the database was created successfully or not. You only have to show the list of the available databases by running the following command:

SHOW DATABASES;

The above output shows that the Demo database is part of the list, hence the database was created successfully.

MariaDB Select Database

For you to be able to use or work on a particular database, you have to select it from the list of the available databases. After selecting a database, you can perform tasks such as creating tables within the database.

To select a database, you should use the USE command. It takes the syntax given below:

USE database_name;

You need to use the Demo database. You can select it by running the following command:

USE Demo;

The above image shows that the MariaDB command prompt has changed from none to the name of the database that has been selected.

You can now go ahead and create tables within the Demo database.

MariaDB – Create Table

For you to be able to create a table, you must have selected a database. The table can be created using the CREATE TABLE statement. Here is the syntax for the command:

CREATE TABLE tableName (columnName columnType);

You can set one of the columns to be the primary key. This column should not allow null values.

We will create two tables within the Demo database, Book, and Price tables. Each table will have two columns.

Let’s begin by creating the Book table with two columns, id and name. Run the following command:

CREATE TABLE Book( id INT NOT NULL AUTO_INCREMENT, name VARCHAR(100) NOT NULL, PRIMARY KEY (id));

The PRIMARY KEY constraint has been used to set the id column as the primary key for the table. The AUTO_INCREMENT property will increment the values of the id column by 1 automatically for each new record inserted into the table. All the columns will not allow null values.

Now, create the second table, the Price table:

CREATE TABLE Price( id INT NOT NULL AUTO_INCREMENT, price float NOT NULL, PRIMARY KEY (id));

The id column has been set as the primary key for the table.

Showing Tables

Now that you have created the two tables, it will be good for you to conform whether the tables were created successfully or not. You can show the list of tables contained in a database by running the following command:

SHOW TABLES;

The above screenshot shows that the two tables were created successfully within the Demo database.

Showing Table Structure

To see the structure of any particular table, you can use the DESCRIBE command, commonly abbreviated as DESC. It takes the following syntax:

DESC TableName;

For example, to see the structure of the table named Book, you can run the following command;

DESC Book;

The table has two columns. To see the structure of the Price table, you can run the following command:

DESC Price;

CRUD and Clauses INSERT

To insert data into a MariaDB table, you should use the INSERT INTO statement. This command takes the syntax given below:

INSERT INTO tableName (column_1, column_2, ... ) VALUES (value1, value2, ... ), (value1, value2, ... ), ...;

The above syntax shows that you have to specify the table columns into which you want to insert data as well as the data that you need to insert.

Let us insert a record into the Book table:

INSERT INTO book (id, name) VALUES(1, 'MariaDB Book');

You have inserted a single record into the table. Insert a record into the Price table:

INSERT INTO price (id, price) VALUES(1, 200);

The record has been created.

SELECT

The SELECT statement helps us to view or see the contents of a database table. To see the contents of the Book table, for example, you need to run the following command:

SELECT * from book;

Now, view the contents of the Price table:

SELECT * from price;

Inserting Multiple Records

It is possible for us to insert multiple records into a MariaDB table at a go. To demonstrate this, run the following example:

INSERT INTO book (id, name) VALUES (2,'MariaDB Book2'), (3,'MariaDB Book3'), (4,'MariaDB Book4'), (5,'MariaDB Book5');

You can query the table to check whether the records were inserted successfully:

SELECT * FROM book;

The records were inserted successfully. Insert multiple records into the Price table by running this example:

INSERT INTO price (id, price) VALUES (2, 250), (3, 220), (4, 190), (5, 300);

Let’s confirm whether the records were created successfully:

SELECT * FROM price;

UPDATE

The UPDATE command helps us to change or modify the records that have already been inserted into a table. You can combine it with the WHERE clause to specify the record that is to be updated. Here is the syntax:

UPDATE tableName SET field=newValue, field2=newValue2,... [WHERE ...]

The UPDATE command can also be combined with clauses such as SET, WHERE, LIMIT, and ORDER BY. You will see this shortly:

Consider the table named Price with the following records:

Let’s change the price of the book with an id of 1 from 200 to 250:

UPDATE price SET price = 250 WHERE id = 1;

The command ran successfully. You can now query the table to see whether the change took place:

The above screenshot shows that the change has been implemented. Consider the table Book with the following records:

Let us change the name of the book named Book to MariaDB Book1. Notice that the book has an id of 1. Here is the command for this:

UPDATE book SET name = “MariaDB Book1” WHERE id = 1;

Check whether the change has been implemented:

The above screenshot shows that the change has been implemented successfully.

In the above examples, we have only changed one column at a time. However, it is possible for us to change multiple columns at a go. Let us demonstrate this using an example.

Let us use the Price table with the following data:

Let us change both the id and the price of the book with an id of 5. We will change its id to 6 and price to 6. Run the following command:

UPDATE price SET id = 6, price = 280 WHERE id = 5;

Now, query the table to check whether the change was made successfully:

The change was made successfully.

Delete

We use the DELETE command when we need to delete either one or many records from a table. Here is the syntax for the command:

DELETE FROM tableName [WHERE condition(s)] [LIMIT numberRows];

Consider the Price table with the following records:

We need to delete the last record from the table. It has an id of 6 and a price of 280. Let us delete the record:

DELETE FROM price WHERE id = 6;

The command ran successfully. Let us query the table to confirm whether the deletion was successful:

The output shows that the record was deleted successfully.

Where

The WHERE clause helps us to specify the exact location where we need to make a change. It is used together with statements such as INSERT, SELECT, UPDATE, and DELETE. Consider the Price table with the following data:

Suppose we need to see the records in which the price is less than 250. We can run the following command:

SELECT * FROM price WHERE price < 250;

All the records in which the price is below 250 have been returned.

The WHERE clause can be combined with the AND statement. Suppose we need to see all records in the Price table where the price is below 250 and id is above 3. We can run the following command:

SELECT * FROM price AND price < 250;

Only one record has been returned. The reason is that it has to meet all the conditions that have been specified, that is, id above 3 and price below 250. If any of these conditions is violated, then the record will not be returned.

The clause can also be combined with the OR command. Let us replace the AND in our previous command with OR and see the kind of output that we receive:

SELECT * FROM price OR price < 250;

We now get 2 records rather than 1. This is because, for a record of qualifying, it only has to meet one of the specified conditions.

This clause is used to specify the data pattern when accessing table data in which an exact match is necessary. It can be combined with the INSERT, UPDATE, SELECT and DELETE statements.

You should pass the pattern of data you are looking for to the clause, and it will return either true or false. Here are the wildcard characters that can be used together with the clause:

%: for matching either 0 or more characters.

_: for matching a single character.

Here is the syntax for the LIKE clause:

SELECT field_1, field_2,... FROM tableName1, tableName2,... WHERE fieldName LIKE condition;

Let us demonstrate how to use the clause with the % wildcard character. Let us use the Book table with the following records:

We need to see all records in which the name begins with M. We can run the following command:

SELECT name FROM book WHERE name LIKE 'M%';

All records have been returned because their names begin with the letter M. To see all names that end with 4, you can run the following command:

SELECT name FROM book WHERE name LIKE '%4';

Only one name has been returned because it’s the only one meeting the condition.

We can also surround the search pattern by the wildcard:

SELECT name FROM book WHERE name LIKE '%DB%';

Other than the % wildcard, the LIKE clause can be used together with the _ wildcard. This is the underscore wildcard, and it will only look for a single character.

Let’s work with the Price table with the following records:

Let us check for the record in which the price is like 1_0. We run the following command:

SELECT * FROM price WHERE price LIKE '1_0';

It has returned the record in which the price is 190. We can also try another pattern:

SELECT * FROM price WHERE price LIKE '_2_';

It is possible for us to use the LIKE clause together with the NOT operator. This will return all the records that don’t meet the specified pattern. For example:

Let us use the Price table with the following records:

Let us find all the records where the price does not start with 2:

SELECT * FROM price WHERE price NOT LIKE '2%';

Only one record does not meet the specified pattern.

Order By

This clause helps us to sort out our records in either ascending or descending order. We use it with the SELECT statement, as shown below:

SELECT expression(s) FROM tables [WHERE condition(s)]

It is possible for us to use this clause without adding either the ASC or DESC part. For example:

We will use the Price table with the following records:

Run the following command against the table:

SELECT * FROM price WHERE price LIKE '2%.' ORDER BY price;

In the above command, we have ordered by the price. The records have been ordered with the prices in ascending order. That means that when we don’t specify the order, the sorting is done in ascending order by default.

Let us run the clause with the DESC option:

SELECT * FROM price WHERE price LIKE '2%' ORDER BY price DESC;

The records have been sorted with the price in descending order as we have specified.

Let us use the ORDER BY clause together with the ASC attribute:

SELECT * FROM price WHERE price LIKE '2%.' ORDER BY price ASC;

The records have been ordered but with the prices in ascending order. This is similar to when we use the ORDER BY clause without either ASC or DESC attributes.

DISTINCT

This clause helps us to do away with duplicates when selecting records from a table. This means that it helps us get unique records. Its syntax is given below:

SELECT DISTINCT expression(s) FROM tableName [WHERE condition(s)];

To demonstrate this, we will use the Price table with the following data:

When we select the price column from the table, we get the following result:

SELECT price FROM Price;

We have two records with a price of 250, creating a duplicate. We need to have only unique records. We can filter these by use of the DISTINCT clause as shown below:

SELECT DISTINCT price FROM Price;

We now don’t have any duplicates in the above output.

From

The FROM clause used for fetching data from a database table. It can also help when joining tables. Here is the syntax for the command:

SELECT columnNames FROM tableName;

To see the contents of the book table, run the following command:

SELECT * FROM price;

The clause can help you to fetch only a single column from a database table. For example:

SELECT price FROM Price;

Advanced Tasks Stored Procedure

A procedure is a MariaDB program that you can pass parameters to. A procedure doesn’t return values. To create a procedure, we use the CREATE PROCEDURE command.

To demonstrate how to create and call a procedure, we will create a procedure named myProcedure() that helps us select the name column from the book table. Here is the procedure:

DELIMITER $ CREATE PROCEDURE myProcedure() BEGIN SELECT name FROM book; END; ;

The procedure has been created. We have simply enclosed the SELECT statement within the BEGIN and END clauses of the procedure.

Now, we can call the procedure by its name as shown below:

CALL myProcedure();

The procedure returns the name column of the book table when called.

We can create a procedure that takes in a parameter. For example, we need to select the name of the book and filter using the book id. We can create the following procedure for this:

DELIMITER $ CREATE PROCEDURE myProcedure2(book_id int) BEGIN SELECT name FROM book WHERE id = book_id; END; ;

Above, we have created a procedure named myProcedure2(). This procedure takes one integer parameter named book_id which is the id of the book whose name we need to see. To see the name of the book with an id of 3, we can call the procedure as follows:

CALL myProcedure2(3);

Function

Unlike procedures, we must pass parameters to functions and a function must return a value. To create a function in MariaDB, we use the CREATE FUNCTION statement. The statement takes the following syntax:

CREATE FUNCTION function-name [(parameter datatype [, parameter datatype]) ] RETURNS datatype [LANGUAGE SQL BEGIN declaration-section executable-section END;

The above parameters are described below:

Parameter Description

DEFINER clause This parameter is optional. If you don’t specify it, the definer will become the user who created the function. If there is a need to specify a different definer, include the DEFINER clause in which the user_name will be the definer of the function.

function_name The name that is to be assigned to this function in the MariaDB.

parameter The parameter(s) passed to the function. During the creation of the function, all parameters are treated as IN parameters (rather than OUT/INOUT parameters).

return_datatype The data type of the return value of the function.

LANGUAGE SQL It affects the portability but not the function.

DETERMINISTIC The function will return one result only when given a number of parameters.

NOT DETERMINISTIC It is possible for the function to return a different result when given a number of parameters.

CONTAINS SQL Informs MariaDB that this function contains SQL. The database will not verify whether this is true.

NO SQL This clause is not used, and it has no impact on your function.

READS SQL DATA Tells MariaDB that this function will use SELECT statements to read data, but it won’t modify the data.

MODIFIES SQL DATA Tells MariaDB that this function will use INSERT, DELETE, UPDATE, and other DDL statements to modify SQL data.

declaration-section This is where local variables should be declared.

executable-section The function code should be added here.

Here is an example MariaDB function:

DELIMITER CREATE FUNCTION sumFunc (x INT ) RETURNS INT DETERMINISTIC BEGIN DECLARE sum INT; SET sum = 0; label1: WHILE sum <= 3000 DO SET sum = sum + x; END WHILE label1; RETURN sum; END; DELIMITER ;

We can then call the above function as follows:

select sumFunc(1000);

The command will return the following:

Once you are done with a function, it will be good for you to delete it. This is easy as you only have to call the DROP FUNCTION statement that takes the following syntax:

DROP FUNCTION function_name;

For example, to drop the function named myFunc, we can run the following command:

DROP FUNCTION myFunc; JOIN

When you need to retrieve data from more than one tables at a go, use MariaDB JOINS. This means that a JOIN works on two or more tables. The following three types of JOINS are supported in MariaDB:

INNER/SIMPLE JOIN

LEFT OUTER JOIN/LEFT JOIN

RIGHT OUTER JOIN/RIGHT JOIN

Let us discuss them one-by-one:

INNER JOIN

The inner join returns all rows from the tables in which the join condition is true. Its syntax is as follows:

SELECT columns FROM table-1 INNER JOIN table-2 ON table-1.column = table-2.column;

For example:

We will use our two tables, books, and book.

The book table has the following data:

The Price table has the following data:

The goal is to join the name column from the Book table and the price column from Price table into a single table. This is possible with an inner join, as demonstrated below:

SELECT book.name, price.price FROM book INNER JOIN price ON chúng tôi = chúng tôi

The command returns the following:

LEFT OUTER JOIN

This join returns all the rows from the left-hand table and only rows in which the join condition is true from the other table. Its syntax is as follows:

SELECT columns FROM table-1 LEFT [OUTER] JOIN table-2 ON table-1.column = table-2.column;

The OUTER keyword has been placed within square brackets because it is optional.

For example:

SELECT book.name, price.price FROM book LEFT JOIN price ON chúng tôi = chúng tôi

The command returns the following:

The last record in the above table has no matching value on the left. That is why it has been replaced with NULL.

RIGHT OUTER JOIN

This join returns all the rows from the right-hand table and only rows in which the join condition is true from the other table. Its syntax is as follows:

SELECT columns FROM table-1 RIGHT [OUTER] JOIN table-2 ON table-1.column = table-2.column;

The OUTER keyword has been placed within square brackets because it is optional.

For example:

SELECT book.name, price.price FROM book RIGHT JOIN price ON chúng tôi = chúng tôi

The command returns the following:

The reason is that all rows in the right-hand table were matched to those in the other table. If some of the rows did not match, we would have NULLs in the first column.

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Notion Buttons – Tutorial With 4 Practical Examples

Notion is the best app for organizing your life. Personally, I use Notion for writing texts, planning my tasks and projects, as well as storing notes.

The unique selling point of Notion is its innovative combination of blocks and databases. However, one small hurdle so far has been the somewhat cumbersome process of making changes in the databases.

Fortunately, this problem has disappeared with one of the recent Notion updates – the introduction of Notion Buttons in March 2023.

In this post, I want to show you what this update means, how to create Notion Buttons and the use cases where you can employ these buttons.

As hinted earlier, with Notion Buttons, you can efficiently perform frequently used actions or insert content, and they can be inserted on any Notion page.

They can be used to:

Insert blocks on a page.

Add pages to a database.

Edit pages in a database.

Open specific pages in your Notion workspace.

Type “/” and search for “Button”.

Now you can label the button and even add an emoji.

Here, you can add the following steps:

Insert Blocks: Insert a Notion block above or below the button. In theory, you can insert any possible Notion block, even another Notion button.

Add Pages to: This will add a page to a database. Simply select the appropriate database and choose the properties that should be filled.

Edit Pages in: Edit pages in a database, so that you can change the date or status, for example. You can also use filters to specify that only pages with specific properties should be modified.

Show Confirmation: This option is useful when you want the user to confirm an action. It can be used, for example, when redirecting them to an external page in the next step.

Open Page: This opens an external page.

Now that you know how to create a Notion button, let’s explore what you can actually do with it. Below, I provide you with 4 specific application examples from my Notion templates:

AI Summarization of Notes in a Zettelkasten

I find this function very important for my Notion Zettelkasten, as it allows me to quickly create readable text from a series of unformatted notes.

Show or Hide All Answers in a Spaced Repetition Template

The Spaced Repetition method is one of the best techniques for reliably memorizing a large amount of information. My Spaced Repetition template now brings this method closer to the Notion community.

To achieve this, I selected the step “Edit Pages” and linked it to the Spaced Repetition database. To hide the answers, I chose the “Reveal Answers” property and instructed the checkbox to remain unchecked everywhere. To show the answers, I created another button where the checkbox is marked as active.

Start or End a Pomodoro Interval

The Pomodoro method is a time management technique developed by Francesco Cirillo in the late 1980s. It divides work into intervals, typically 25 minutes long, to ensure regular breaks for regeneration.

Francesco Cirillo used to measure time with his Pomodoro kitchen timer, hence the name Pomodoro.

My Notion template allows you to implement the Pomodoro technique directly in Notion and connect your work tasks with your Notion task manager.

The only drawback: The template does not include a Pomodoro kitchen timer :(.

With the help of a Notion button, you can start a new Pomodoro interval or end an ongoing interval. The database will track the duration of the interval, allowing you to monitor your work time.

To start a new Pomodoro interval, the Notion button adds a new page to the Pomodoro database. The start time is set to “Now,” and the status is set to “Active.”

The button to end the Pomodoro interval updates the database and all active pages. The end time is set to “Now,” and the status is changed to “Done.”

Adding New Habits and Marking them as Completed

In my Habit Compass template, I use Notion buttons to add new habits for the day and check them off.

Users of the template are invited to customize the button. For example, they can change the habit’s name and indicate which vision from the vision board it should be associated with.

“Check Habit” modifies database entries and marks the respective habit as completed.

In my tutorial, I showed you how I use Notion buttons in my workspace. However, I’m also curious about your experiences. How do you use Notion buttons in your work routine? Do you have any useful tips or tricks you’d like to share?

I look forward to hearing from you!

Yours, Philipp

Learn Php Require_Once With Programming Examples

Introduction to PHP require_once

The require_once function of the PHP Programming Language helps in including a PHP file in another PHP file when that specific PHP file is included more than one time and we can consider it as an alternative for include function. If a PHP script file already included inside our required PHP file then that including will be ignored and again the new PHP file will be called just by ignoring the further inclusions. Suppose if chúng tôi is one of the PHP script file calling chúng tôi with require_once() function and it don’t fine chúng tôi chúng tôi stops executing and will cause a FATAL ERROR.

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Syntax:

require_once(' PHP file with the path '); How require_once works in PHP?

The require_once function of the PHP language works only once even though if we include a specific PHP file or files inside of the main PHP script file. We can include a PHP script file/files as many times as we need but only once the specific PHP will be included and executed for the display of the output of the program. This require_once concept works only for PHP 4, PHP 5, PHP 7 versions and may be for PHP 7+ versions it will work. This first check whether the specific .PHP file is already included or not. If already included then the require_once function will leave including same .PHP file. If not, the specific .PHP file will be included. It is a very useful statement of the PHP Programming Language.

Examples

Below are the examples to implement the same:

Example #1

Syntax of the Main PHP File:

</head&gt Engineers, Physics Nerds, Tech Enthusiasts to provide the better content.

Syntax of chúng tôi file:

<?php echo “This is by implementing the require_once statement of PHP..”; echo “Now you are in the chúng tôi files content!! because of require_once but calling twice don’t works with this”;

Syntax of chúng tôi file:

<?php echo “This is by implementing the require_once statement of PHP..”; echo “Now you are in the chúng tôi files content because of require_once but calling twice don’t works with this!!”;

Output:

Example #2

This is also another example of implementing this function. Here in the main original file (index.php) file, require_once() function is used 7 times to include chúng tôi In the chúng tôi file, only the chúng tôi file is included using the method few times. Then in the chúng tôi file, only chúng tôi file a few times and it is to include the content of the chúng tôi Here we didn’t mention any text in the chúng tôi files but at last in the chúng tôi file only sum code is implemented and that code will be executed and displayed along with the main original PHP file’s content/code. Footer code will be displayed inside of the horizontal lines. You can check the output for a better understanding.

Syntax of the main chúng tôi file:

<hrgt; Engineers, Physics Nerds, Tech Enthusiasts to provide better content.

Syntax of the chúng tôi file:

<?php require_once 'header1.php'; require_once 'header1.php'; require_once 'header1.php';

<?php require_once 'footer1.php'; require_once 'footer1.php'; require_once 'footer1.php'; require_once 'footer1.php';

Syntax of the chúng tôi file:

<?php $i=10; $j=90; $k = $i + $j; echo "This content is included from the chúng tôi file - Code from chúng tôi file"; echo "This the sum of $i and $j values :: "; echo $k;

Output:

Advantages Conclusion

I hope you learned what is the definition of the require_once function of the PHP Programming Language along with its syntax, How the PHP require_once function works along with some examples of which illustrate function, Advantages, etc. to understand this concept better and so easily.

Node.js Tutorial For Beginners: Learn Step By Step In 3 Days

Introduction to Node.js

The modern web application has really come a long way over the years with the introduction of many popular frameworks such as bootstrap, Angular JS, etc. All of these frameworks are based on the popular JavaScript framework.

But when it came to developing server-based applications, there was a kind of void, and this is where chúng tôi came into the picture.

Node.js is also based on the JavaScript framework, but it is used for developing server-based applications. While going through the entire tutorial, we will look into chúng tôi in detail and how we can use it to develop server-based applications.

Node.js Syllabus Node.js Basics for Beginners

Node.js Advance Stuff! Know the Difference! Node.js Interview Questions & Tutorial PDF

👉 Lesson 1 Node.js Interview Questions — Top 25 chúng tôi Interview Questions and Answers

👉 Lesson 2 Node.js Tutorial PDF — Download chúng tôi Tutorial PDF for Beginners

What is Node.js?

Node.js is an open-source, cross-platform runtime environment used for the development of server-side web applications. chúng tôi applications are written in JavaScript and can be run on a wide variety of operating systems.

Node.js is based on an event-driven architecture and a non-blocking Input/Output API that is designed to optimize an application’s throughput and scalability for real-time web applications.

Over a long period of time, the framework available for web development were all based on a stateless model. A stateless model is where the data generated in one session (such as information about user settings and events that occurred) is not maintained for usage in the next session with that user.

A lot of work had to be done to maintain the session information between requests for a user. But with chúng tôi there is finally a way for web applications to have real-time two-way connections, where both the client and server can initiate communication, allowing them to exchange data freely.

Why use Node.js?

We will have a look into the real worth of chúng tôi in the coming chapters, but what is it that makes this framework so famous. Over the years, most of the applications were based on a stateless request-response framework. In these sort of applications, it is up to the developer to ensure the right code was put in place to ensure the state of web session was maintained while the user was working with the system.

But with chúng tôi web applications, you can now work in real-time and have a 2-way communication. The state is maintained, and either the client or server can start the communication.

Features of Node.js

Let’s look at some of the key features of Node.js

This is quite different from other programming languages. A simple example of this is given in the code below

var fs = require('fs'); fs.readFile("Sample.txt",function(error,data) { console.log("Reading Data completed"); });

The above code snippet looks at reading a file called chúng tôi In other programming languages, the next line of processing would only happen once the entire file is read.

But in the case of chúng tôi the important fraction of code to notice is the declaration of the function (‘function(error,data)’). This is known as a callback function.

So what happens here is that the file reading operation will start in the background. And other processing can happen simultaneously while the file is being read. Once the file read operation is completed, this anonymous function will be called, and the text “Reading Data completed” will be written to the console log.

Node uses the V8 JavaScript Runtime engine, the one which is used by Google Chrome. Node has a wrapper over the JavaScript engine which makes the runtime engine much faster and hence the processing of requests within Node also become faster.

Handling of concurrent requests – Another key functionality of Node is the ability to handle concurrent connections with a very minimal overhead on a single process.

The chúng tôi library uses JavaScript – This is another important aspect of development in chúng tôi A major part of the development community is already well versed in javascript, and hence, development in chúng tôi becomes easier for a developer who knows javascript.

There is an active and vibrant community for the chúng tôi framework. Because of the active community, there are always keys updates made available to the framework. This helps to keep the framework always up-to-date with the latest trends in web development.

Who uses Node.js

Node.js is used by many large companies. Below is a list of a few of them.

Paypal – A lot of sites within Paypal have also started the transition onto Node.js.

LinkedIn – LinkedIn is using chúng tôi to power their Mobile Servers, which powers the iPhone, Android, and Mobile Web products.

Mozilla has implemented chúng tôi to support browser APIs which has half a billion installs.

eBay hosts their HTTP API service in Node.js

When to Use Node.js

Node.js is best for usage in streaming or event-based real-time applications like

Chat applications

Game servers – Fast and high-performance servers that need to processes thousands of requests at a time, then this is an ideal framework.

Good forcollaborative environment – This is good for environments which manage documents. In a document management environment, you will have multiple people who post their documents and do constant changes by checking out and checking in documents. So chúng tôi is good for these environments because the event loop in chúng tôi can be triggered whenever documents are changed in a document managed environment.

Streaming servers – Another ideal scenario to use Node is for multimedia streaming servers wherein clients have request’s to pull different multimedia contents from this server.

Node.js is good when you need high levels of concurrency but less amount of dedicated CPU time.

Best of all, since chúng tôi is built on javascript, it’s best suited when you build client-side applications which are based on the same javascript framework.

When to not use Node.js

Node.js can be used for a lot of applications with various purposes. The only scenario where it should not be used is where there are long processing times, which is required by the application.

Node is structured to be single-threaded. If an application is required to carry out some long-running calculations in the background, it won’t be able to process any other requests. As discussed above, chúng tôi is used best where processing needs less dedicated CPU time.

Comprehensive Guide To R Packages With Syntax & Code

Introduction to R Packages

R packages are a set of predefined functions as a library to be used while deploying the R program to care for reusability and less code approach R programs. R packages are externally developed and can be imported to the R environment in order to use the available function which belongs to that package. R packages are managed by the R community network known as CRAN for providing and provisioning with the R programming language. Apart from the standard R packages, there are several external packages available for use in the R program. One of the popular graphical packages in R is ggplot2.

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Where do we Find Packages?

Packages are available on the internet through different sources. However, there are certain trusted repositories from where we can download the packages.

Here are the two important repositories that are available online.

CRAN(Comprehensive R Archive Network): This is the official R community with a network of FTP and webservers that contains the latest code and documentation of R. Before you post your packages online, it goes through a series of tests that adheres to CRAN policy.

GitHub: GitHub is another famous repository but not specific to chúng tôi online community can share their packages with other people, and it is used for version control as well. GitHub is open-source and doesn’t have any review process.

List of Useful R Packages

There are several packages in R and can be downloaded from CRAN or GitHub. Below are the packages that can be used for specific purposes.

1. Loading the Data from External Sources

DBI: To establish communication between the relational database and R.

RSQlite: It is used to read data from relational databases.

2. Data Manipulation

Dplyr: It is used for data manipulation like subsetting, provides shortcuts to access data and generates sql queries.

Tidyr – It is used to convert data into tiny formats.

stringr– manipulate string expressions and character strings.

lubridate- To work with data and time.

3. Data Visualization

Rgl: To work on 3D visualizations.

ggvis: To create and build grammar of graphics.

googlevis: To use google visualization tools in R.

4. Web-Based Packages

XML: To read and write XML documents in R.

Jsonlite: To read json data tables.

Obtaining R Packages

available.packages(): There are approximately 5200 packages available in the CRAN network.

CRAN has task views that group packages under a particular topic.

Installing R Packages

We can install packages directly through IDE or through commands. To install packages, we use the below function and specify the package name.

Syntax:

install.packages()

Code:

install.packages(“ggplot2”)

The above code installs the ggplot2 package and its dependent packages, if any.

We can install several packages at a time by specifying the package’s names under a character vector.

Syntax:

install.packages(c(“package 1”,”package 2”,”package 3”))

Code:

install.packages(c(“ggplot2”,”slidify”,”deplyr”))

Installing using R Studio Loading R Packages

After installing the R package, we need to load them into R to start making use of the installed packages.

We use the below function to load the packages.

Syntax:

library(package name)

Note: The package name need not be given in quotes.

Code:

There are certain packages that display messages when loaded. Some of them don’t. We can see the details of the library installed with the help of the below code.

Code:

search()

Output:

“package:lattice” “package:ggplot2” “package:makeslides”

“package:knitr” “package:slidify” “tools:rstudio”

Creating Your own Package

Before we create our own package, we should keep the below checklist in our mind before we proceed to create a package.

Organizing the code is one of the most important things while writing code in the package. We lose half the time searching for the code location instead of improving the code. Put all the files in a folder that is easily accessible.

Documenting the code helps you understand the purpose of the code. When we don’t revisit the code often, we forget why we have written the code in a certain way. It can also help people to understand your code better when shared with them.

Sharing the scripts through email has become archaic. The easy way is to upload your code and distribute it on GitHub. It is possible you get feedback that can help you enhance the code.

To create your own package, we have to install the devtools package.

Code:

install.packages("devtools")

To help with the documentation, we can use the below package.

Code:

After installing the package devtools, you can create your own package.

Code:

devtools::create ("packagename")

In the place of “packagename”, you can give the name you wish. You can now add your functions under this package.

You can create the same filename as your function name.

Syntax:

Devtools:create(“firstpackage”)

Distributing Package

You can distribute your package on GitHub by using the devtools package.

We use the below code to distribute our package on Github.

Code:

devtools::install_github("yourusername/firstpackage")

You can give your github username and package name you have created above.

Here are the Required Files for a Package

Functions

Documentation

Data

Once we have all the above files, we are good to post them in the repository.

A Quick Glance On Mariadb Insert

Introduction to MariaDB insert

MariaDB is one of the world-famous open source database systems. MariaDB works similar to MySQL, which means most of the statements are similar to MySQL, in which that insert statement is similar in MySQL and MariaDB. The insert statement is used to insert records or insert new rows into the table. With the help of an insert statement or command, we can insert a single row or multiple rows at a time, and it comes under the data manipulation command category. When we insert a record into the table by using an insert statement, then we must insert a value for every not null column. We can delete the column from the insert statement if the column allows null values.

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Syntax of MariaDB insert

For single-row insertion operation.

insert into table name (colm_name_1 , colm_name_2,….. colm_name_N) values (statement 1, statement 2,…..statement N), (statement 1, statement 2,…..statement N),………;

Explanation:

insert into: The insert into command is used to insert records into the specified table.

table name: Table name means an actual table that we need to insert new records.

column name: It is a specified column name from the table to insert the values.

statement: Statement is used to assign the values to the column in the table, so column name 1 is assigned values of statement 1; similarly, we consider all statements.

The syntax for multiple row insertion operation by using sub select statement in MariaDB.

insert into table name (colm_name_1 , colm_name_2,….. colm_name_N) select statement 1, statement 2 from source table name [Where condition]

Explanation:

Basically, this statement is useful when we insert records from another table.

Some of the parameters are similar like the first syntax here; some parameters are added as follows:

source table name: Source Table Name means we can insert records from another table that table name means source table name.

where condition: Where condition is an optional part of this syntax, but when we use where condition in a statement that must be stratified insert condition.

How does insert Statement Works in MariaDB?

Basically, insert statement allows us to add new records into the existing table by using the above syntax. Normally syntax of insert statement followed by the table name, after that column name and values this is a simple structure of insert statement.

Let’s see how to insert a statement in MariaDB as follows:

Insert statement uses single or double quotes for the string value.

If we want to skip column name from the column list, then we must ensure that the skip column has a default value; otherwise, an error will occur.

In MariaDB, we use the following expression when we skip column name from column list at the time of insert operation.

The column name has an auto_increment property for the next sequential integer.

Sometimes column names have a default value.

If the value is NULL, then a column is a null column.

Examples of MariaDB insert

Let’s see how MariaDB insert statements work with the help of an example as follows:

For insertion operation, we need a table to create a table by using the following statement as follows.

Code:

create table emp( emp_id int auto_increment, emp_name varchar(255) not null, emp_dept varchar(255) not null, emp_address varchar(255) not null, primary key(emp_id) );

Explanation:

With the help of the above statement, we created emp with different parameters such as emp_id, emp_name, emp_dept, emp_address with different data types as shown in the above statement. Here we assign emp_id as the primary key. The result of the above statement we illustrate by using the following snapshot.

Output:

Now we can insert records into the emp table by using the following statement as follows.

Insert into emp(emp_name, emp_dept, emp_address) values ("John", "Mech", "Mumbai"); select * from emp;

Explanation:

With the help of a statement, we inserted a single row into the emp table; see in this example, we only inserted one row. The result of the above statement we illustrate by using the following snapshot.

Output:

Now let’s see how we can insert multiple rows by using insert into a statement as follows.

Code:

Insert into emp(emp_name, emp_dept, emp_address) values ("Jenny", "Comp", "Londan"), ("Sam", "Account", "Mumbai") ; select * from emp;

Explanation:

In the above example, we insert two rows at a time as shown in the above statement; here, we inserted two records into the emp table with different values. The result of the above statement we illustrate by using the following snapshot.

Output:

We have another table name as a customer with different attributes such as cust_id, cust_name cust_dept and cust_address. Now we need to insert a record from the emp table to the customer by using the following statement.

Code:

select emp_name, emp_dept, emp_address from emp where emp_id=1; insert into customer (cust_id, cust_name, cust_dept, cust_address) select 1, emp_name, emp_dept, emp_address from emp where emp_id=1;

Explanation:

In the above example, we combine select and insert statements as shown in the above statement. The result of the above statement we illustrate by using the following snapshot.

Output:

Code:

select * from customer;

Output:

Rules and Regulation for Using the insert Statement

Basically, every time we cannot insert a value for a single column, some column we left as blank and provides a default value.

In some cases, columns automatically generate their own value; in this case, there is no need to try and insert our own values.

In insert statements, we always match the order of values and column, data type and number.

If the value of the column is string, data, time or character, at that time, we need to enclose them in single quotes, and if the value of character is number or integer, then there is no need to quote.

If we don’t want to insert values into the column list, we must insert values into all columns into the table and maintain the order of values.

Conclusion

From the above article, we saw the basic syntax of MariaDB insert statements, and we also saw different examples of insert statements. We also saw the rules of MariaDB insert statements. From this article, we saw how and when we use MariaDB insert statements.