mysqli_select_db()期望参数1为mysqli，给定字符串 [英] mysqli_select_db() expects parameter 1 to be mysqli, string given

问题描述

我是Mysqli_ *的新手，并且出现以下错误:

I am new to Mysqli_* and I am getting these errors:

警告:mysqli_select_db()期望参数1为mysqli，字符串 在第11行的D:\ Hosting \ 9864230 \ html \ includes \ connection.php中给出

Warning: mysqli_select_db() expects parameter 1 to be mysqli, string given in D:\Hosting\9864230\html\includes\connection.php on line 11

警告:mysqli_error()期望恰好有1个参数，其中0表示 第13行的D:\ Hosting \ 9864230 \ html \ includes \ connection.php

Warning: mysqli_error() expects exactly 1 parameter, 0 given in D:\Hosting\9864230\html\includes\connection.php on line 13

数据库选择失败:

<?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());
}
?>

推荐答案

您的参数顺序错误.根据文档

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');
}

?>

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