I am new to Mysqli_* and I am getting these errors:
Warning: mysqli_select_db() expects parameter 1 to be mysqli, string given in D:\Hosting\9864230\html\includes\connection.php on line 11
Warning: mysqli_error() expects exactly 1 parameter, 0 given in D:\Hosting\9864230\html\includes\connection.php on line 13
Database selection failed:
<?php
require("constants.php");
// 1. Create a database connection
$connection = mysqli_connect(DB_SERVER,DB_USER,DB_PASS);
if (!$connection) {
die("Database connection failed: " . mysqli_error());
}
// 2. Select a database to use
$db_select = mysqli_select_db(DB_NAME,$connection);
if (!$db_select) {
die("Database selection failed: " . mysqli_error());
}
?>
Your arguments are in the wrong order. The connection comes first according to the docs
<?php
require("constants.php");
// 1. Create a database connection
$connection = mysqli_connect(DB_SERVER,DB_USER,DB_PASS);
if (!$connection) {
error_log("Failed to connect to MySQL: " . mysqli_error($connection));
die('Internal server error');
}
// 2. Select a database to use
$db_select = mysqli_select_db($connection, DB_NAME);
if (!$db_select) {
error_log("Database selection failed: " . mysqli_error($connection));
die('Internal server error');
}
?>
// 2. Select a database to use
$db_select = mysqli_select_db($connection, DB_NAME);
if (!$db_select) {
die("Database selection failed: " . mysqli_error($connection));
}
You got the order of the arguments to mysqli_select_db()
backwards. And mysqli_error()
requires you to provide a connection argument. mysqli_XXX is not like mysql_XXX, these arguments are no longer optional.
Note also that with mysqli you can specify the DB in mysqli_connect()
:
$connection = mysqli_connect(DB_SERVER, DB_USER, DB_PASS, DB_NAME);
if (!$connection) {
die("Database connection failed: " . mysqli_connect_error();
}
You must use mysqli_connect_error()
, not mysqli_error()
, to get the error from mysqli_connect()
, since the latter requires you to supply a valid connection.
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