Uso e exemplo da função PHP mysqli_connect()

PHP MySQLi Manual

A função mysqli_connect() abre uma nova conexão com o servidor MySQL.

Definição e uso

mysqli_connect()A função cria uma conexão com o servidor MySQL e retorna a conexão como objeto.

Sintaxe

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

Parâmetro

Retorno do valor

Se a conexão com o servidor MySQL foi estabelecida com sucesso. A função PHP mysqli_connect() retorna o objeto de conexão. Se a conexão falhar, essa função retorna um valor booleano.false.

PHP version

This function was first introduced in PHP version5introduced in and can be used in all higher versions.

Online example

The following examples demonstratemysqli_connect()Usage of the function (procedural style):

<?php
　　　$host = "localhost";
　　　$username = "root";
　　　$passwd = "password";
　　　$dbname = "mydb";
　　　//Establish connection
　　　$con = mysqli_connect($host, $username, $passwd, $dbname);
　　　if ($con) {
　　　　　　print("Successfully established connection");
　　　} else {
　　　　　　print("Connection failed ");
　　　}
?>

Output results

Successfully established connection

Online example

In an object-oriented style, you can useNew mysqli()The constructor creates a connection, as shown below:

<?php
　　　$host = "localhost";
　　　$username = "root";
　　　$passwd = "password";
　　　$dbname = "mydb";
　　　//Establish connection
　　　$con = new mysqli($host, $username, $passwd, $dbname);
　　　if ($con-> connect_errno) {
　　　　　　print("Connection failed");
　　　} else {
　　　　　　print("Successfully established connection");
　　　}
　　　//Close connection
　　　$con　-> close();
?>

Output results

Successfully established connection

Online example

You can also call this function without passing any parameters, as shown below:

<?php
　　　//Establish connection
　　　$con = @mysqli_connect();
　　　if ($con) {
　　　　　　print("Successfully established connection");
　　　} else {
　　　　　　print("Connection failed ");
　　　}
?>

Output results

Connection failed

Online example

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

Output results

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

PHP MySQLi Manual