Question

当我运行代码时，它会显示此错误。 “mysqli_query（）期望参数1为mysqli，null为”

<?php

function confirm_query($result_set) {
if (!$reslt_set) {
    die("database query failed");
}
}

function find_all_subjects() {
global $connection;
$query = "SELECT * ";
$query .= "FROM subjects ";
$query .= "WHERE visible=1 ";
$query .= "ORDER BY position ASC ";
$subject_set = mysqli_query($connection, $query);
confirm_query($subject_set);
return $subject_set;
}
?>

Answer 1

如果这是您的完整文件，那么$connection将为空（null），您不会在任何地方创建连接。

您可能正在另一个文件中创建连接，因此global $connection;但是您需要包含此文件才能获得连接。

Answer 2

您正在混合mysql_和mysqli个功能。这可能是你的问题。你不能在代码中混合使用mysqli和mysql函数。

Answer 3

试试这个。

$link = mysqli_connect("localhost", "my_user", "my_password", "world");

/* check connection */
if (mysqli_connect_errno()) {
    printf("Connect failed: %s\n", mysqli_connect_error());
    exit();
}

/* Create table doesn't return a resultset */
if (mysqli_query($link, "CREATE TEMPORARY TABLE myCity LIKE City") === TRUE) {
    printf("Table myCity successfully created.\n");
}

/* Select queries return a resultset */
if ($result = mysqli_query($link, "SELECT Name FROM City LIMIT 10")) {
    printf("Select returned %d rows.\n", mysqli_num_rows($result));

    /* free result set */
    mysqli_free_result($result);
}

仅限php.net

mysqli_query（）期望参数1为mysqli，null给定:(

3 个答案: