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Khóa học miễn phí MariaDB – Select Database nhận dự án làm có lương

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MariaDB – Select Database

After connecting to MariaDB, you must select a database to work with because many databases may exist. There are two ways to perform this task: from the command prompt or through a PHP script.

The Command Prompt

In choosing a database at the command prompt, simply utilize the SQL command ‘use’ −

[root@host]# mysql -u root -p

Enter password:******

mysql> use PRODUCTS;

Database changed

mysql> SELECT database();  
+-------------------------+ 
| Database                | 
+-------------------------+ 
| PRODUCTS                | 
+-------------------------+

Once you select a database, all subsequent commands will operate on the chosen database.

Note − All names (e.g., database, table, fields) are case sensitive. Ensure commands conform to the proper case.

PHP Select Database Script

PHP provides the mysql_select_db function for database selection. The function uses two parameters, one optional, and returns a value of “true” on successful selection, or false on failure.

Syntax

Review the following select database script syntax.

bool mysql_select_db( db_name, connection );

The description of the parameters is given below −

S.No Parameter & Description
1

db_name

This required parameter specifies the name of the database to use.
2

connection

When not specified, this optional parameter uses the most recent connection used.

Try the following example code for selecting a database −

<html>
   <head>
      <title>Select a MariaDB Database</title>
   </head>

   <body>
      <?php
         $dbhost = ''localhost:3036
         $dbuser = ''guest1
         $dbpass = ''guest1a
         $conn = mysql_connect($dbhost, $dbuser, $dbpass);
      
         if(! $conn ) {
            die(''Could not connect: '' . mysql_error());
         }
         echo ''Connected successfully
         
         mysql_select_db( ''PRODUCTS'' );
         mysql_close($conn);
      ?>
   </body>
</html>

On successful selection, you will see the following output −

mysql> Connected successfully

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