mysqli

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

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MySQLi – Select Database

Once you get connected with the MySQL server, it is required to select a database to work with. This is because there might be more than one database available with the MySQL Server.

Selecting MySQL Database from the Command Prompt

It is very simple to select a database from the mysql> prompt. You can use the SQL command use to select a database.

Example

Here is an example to select a database called TUTORIALS −

[root@host]# mysql -u root -p
Enter password:******
mysql> use TUTORIALS;
Database changed
mysql>

Now, you have selected the TUTORIALS database and all the subsequent operations will be performed on the TUTORIALS database.

NOTE − All the database names, table names, table fields name are case sensitive. So you would have to use the proper names while giving any SQL command.

Selecting a MySQL Database Using PHP Script

PHP uses mysqli_select_db function to select the database on which queries are to be performed. This function takes two parameters and returns TRUE on success or FALSE on failure.

Syntax

mysqli_select_db ( mysqli $link , string $dbname ) : bool

Sr.No. Parameter & Description
1

$link

Required – A link identifier returned by mysqli_connect() or mysqli_init().
2

$dbname

Required – Name of the database to be connected.

Example

Try the following example to select a database −

Copy and paste the following example as mysql_example.php −

<html>
   <head>
      <title>Selecting MySQL Database</title>
   </head>
   <body>
   <?php
      $dbhost = ''localhost
      $dbuser = ''root
      $dbpass = ''root@123
      $conn = mysqli_connect($dbhost, $dbuser, $dbpass);

      if(! $conn ) {
         die(''Could not connect: '' . mysqli_error($conn));
      }
      echo ''Connected successfully<br />
      
      $retval = mysqli_select_db( $conn, ''TUTORIALS'' );

      if(! $retval ) {
         die(''Could not select database: '' . mysqli_error($conn));
      }
      echo "Database TUTORIALS selected successfullyn";
      mysqli_close($conn);
   ?>
   </body>
</html>

Output

Access the mysql_example.php deployed on apache web server and verify the output.

Database TUTORIALS selected successfully

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