Hello folks! welcome back to a new edition of our tutorial on PHP. In this tutorial guide, we are going to be studying about the PHP mysqli_select_db() Function.
The built-in mysqli_select_db() function in PHP accepts a string value that represents an existing database and, makes it as the default database.
The built-in mysqli_select_db() function in PHP accepts a string value that represents an existing database and, makes it as the default database.
Syntax
Following below is the syntax to use this function -
mysqli_select_db($con name)
Parameter Details
Sr.No | Parameter & Description |
---|---|
1 | con(Mandatory) This is an object representing a connection to MySQL Server. |
2 | name(Mandatory) This is a string value representing the name of an existing database which you need to make as the default database. |
Return Value
This built-in PHP function returns true if the operation is successful otherwise, false on failure.
PHP Version
This PHP function was first introduced in PHP version 5 and works in all the later versions.
Example1
The following example demonstrates the usage of the built-in PHP mysqli_select_db() function (in procedural style) -
<?php //Creating a connection $con = mysqli_connect("localhost", "root", "password", "mydb"); //Selecting the database mysqli_query($con, "CREATE DATABASE NewDatabase"); mysqli_select_db($con, "NewDatabase"); //Retrieving the current database name $res = mysqli_query($con, "SELECT DATABASE()"); while ($row = mysqli_fetch_row($res)) { print("Current Database: ".$row[0]); } //Closing the connection mysqli_close($con); ?>
Output
When the above code is executed, it will produce the following result -
Current Database: newdatabase
Example2
In an object oriented style the syntax of this built-in function is $con->select_db(); The following below is an example of this PHP function in an object oriented style $minus;
<?php //Creating a connection $con = new mysqli("localhost", "root", "password", "mydb"); //Retrieving the current database name $res = $con->query("SELECT DATABASE()"); while ($row = $res->fetch_row()) { print("Initial Database: ".$row[0]."\n"); } //Selecting the database $con->query("CREATE DATABASE NewDatabase"); $con->select_db("NewDatabase"); //Retrieving the current database name $res = $con->query("SELECT DATABASE()"); while ($row = $res->fetch_row()) { print("Current Database: ".$row[0]); } //Closing the connection $res = $con -> close(); ?>
Output
When the above code is executed, it will produce the following result -
Initial Database: mydb Current Database: newdatabase
Example3
Instead of specifying the database at the time of connection, you can also choose it later using this built-in function as shown below -
<?php //Creating a connection $con = mysqli_connect("localhost", "root", "password"); //Selecting the database mysqli_select_db($con, "mydb"); print("Database Selected ..."."\n"); mysqli_query($con, "CREATE TABLE IF NOT EXISTS my_team(ID INT, First_Name VARCHAR(255), Last_Name VARCHAR(255), Place_Of_Birth VARCHAR(255), Country VARCHAR(255))"); print("Table Created ..."."\n"); //Inserting a records into the my_team table mysqli_query($con, "insert into my_team values(1, 'Kennedy', 'Nkpara', 'PortHarcourt', 'Nigeria')"); mysqli_query($con, "insert into my_team values(2, 'Jonathan', 'Trott', 'CapeTown', 'SouthAfrica')"); mysqli_query($con, "insert into my_team values(3, 'Queen', 'Dauglas', 'Texas', 'UnitedStates')"); mysqli_query($con, "insert into my_team values(4, 'Paul', 'Francis', 'Texas', 'UnitedStates')"); print("Records Inserted ..."."\n"); //Closing the connection mysqli_close($con); ?>
Output
When the above code is executed, it will produce the following result below -
Database Selected... Table Created... Records Inserted...
Example4
Try the following example below -
<?php $connection_mysql = mysqli_connect("localhost", "root", "password","mydb"); if (mysqli_connect_errno($connection_mysql)){ echo "Failed to connect to MySQL: " . mysqli_connect_error(); } $res = mysqli_select_db($connection_mysql,"testdb"); if($res){ echo "Database Selected"; }else{ echo "Error Occurred"; } mysqli_close($connection_mysql); ?>
Output
When the above code is executed, it will produce the following result below -
Database Selected
Alright guys! This is where we are going to be rounding up for this tutorial post. In our next tutorial, we are going to be discussing about the mysqli_set_charset() Function in PHP.
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