php - 连接数据库后执行函数

Question

我有一个问题，我正在尝试执行可以执行 SQL 语法的函数，但是当我尝试执行它时，mysqli_query 会导致错误，因为此函数需要两个参数。但是我有另一个连接数据库的功能，我该如何解决这个问题？

function connect_to_database($servername, $username,$password,$dbname) {
    $conn = new mysqli($servername, $username, $password, $dbname);
    if ($conn->connect_error) {
        die("Connection failed: " . $conn->connect_error);
    }
}
    
function execute($get_sql) {
    $sql[0] = $get_sql;
    mysqli_query($sql[0]);
}
    
connect_to_database("localhost","root","root","m1_14");
execute("INSERT INTO teszt_1 (email,username,order,createdate) VALUES ('test@gmail.com','test','test',NOW())");

Answer 1

您需要将变量声明为“全局”:

<?php
    $conn = null; // ◄■■■
    $result = null; // ◄■■■

    function connect_to_database($servername, $username,$password,$dbname)
    { global $conn; // ◄■■■
        $conn = new mysqli($servername, $username, $password, $dbname);
        if ($conn->connect_error)
        {
            die("Connection failed: " . $conn->connect_error);
        }
    }

    function execute($get_sql)
    { global $conn; // ◄■■■
      global $result; // ◄■■■
        $sql[0] = $get_sql;
        $result = mysqli_query($conn,$sql[0]); // ◄■■■ $CONN AND $RESULT.
    }

    connect_to_database("localhost","root","root","m1_14");
     execute("INSERT INTO teszt_1 (email,username,order,createdate) " .
             "VALUES ('test@gmail.com','test','test',NOW())");

    execute("select * from teszt_1");

    foreach ( $result as $row ) // ◄■■■ USE $RESULT HERE.
      echo $row["email"];

全局变量可让您将值从一个函数传递到另一个函数。

如果是“插入”，您不需要 $result，如果是“选择”，您可以使用 $result 来访问值。