PHP mysqli_connect() Function

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Definition and Usage

The mysqli_connect() function establishes a connection with MySQL server and returns the connection as an object.

Syntax

mysqli_connect([$host, $username, $passwd, $dname, $port, $socket] )

Parameters

Sr.No Parameter & Description
1

host(Optional)

This represents a host name or an IP address. If you pass Null or localhost as a value to this parameter, the local host is considered as host.
2

username(Optional)

This represents a user name in MySQL.
3

passwd(Optional)

This is represents the password to the given user.
4

dname(Optional)

This represents the default database in which the queries should be performed.
5

port(Optional)

This represents the port number at which you want to establish a connection to MySQL Server.
6

socket(Optional)

This represents the socket that is to be used.

Return Values

If a connection got established successfully to the MySQL server. The PHP mysqli_connect() function returns the connection object. Incase of an unsuccessful connection this function returns the boolean value false.

PHP Version

This function was first introduced in PHP Version 5 and works works in all the later versions.

Example

Following example demonstrates the usage of the mysqli_connect() function (in procedural style) −

<?php
   $host = "localhost";
   $username  = "root";
   $passwd = "password";
   $dbname = "mydb";

   //Creating a connection
   $con = mysqli_connect($host, $username, $passwd, $dbname);

   if($con){
      print("Connection Established Successfully");
   }else{
      print("Connection Failed ");
   }
?>

This will produce following result −

Connection Established Successfully

Example

In object oriented style you can use the new mysqli() construct to create a connection as follows $minus;

<?php
   $host = "localhost";
   $username  = "root";
   $passwd = "password";
   $dbname = "mydb";

   //Creating a connection
   $con = new mysqli($host, $username, $passwd, $dbname);

   if($con->connect_errno){
      print("Connection Failed ");
   }else{
      print("Connection Established Successfully");
   }

   //Closing the connection
   $con -> close();
?>

This will produce following result −

Connection Established Successfully

Example

You can also invoke this function without passing any parameters as shown below −

<?php
   //Creating a connection
   $con = @mysqli_connect();

   if($con){
      print("Connection Established Successfully");
   }else{
      print("Connection Failed ");
   }
?>

This will produce following result −

Connection Failed

Example

<?php
   $connection_mysql = @mysqli_connect("localhost", "root", "wrong_password", "mydb");
   
   if (mysqli_connect_errno($connection_mysql)){
      echo "Failed to connect to MySQL: " . mysqli_connect_error();
	  exit();
   }   
   echo ("Connection established successfully");    
   mysqli_close($connection_mysql);
?>

This will produce following result −

Failed to connect to MySQL: Access denied for user 'root'@'localhost' (using password: YES)
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