Warning: mysqli_fetch_assoc() expects parameter 1 to be mysqli_result, bool given in

This warning usually indicates that your SQL query has failed, resulting inmysqli_query()Returns a boolean value.falseInstead of being effectivemysqli_resultObject. This could be due to various reasons, for example:

• The SQL query contains a syntax error or a logical error.
• The data table or database does not exist or is inaccessible.
• An error occurred while connecting to the database, such as invalid credentials or a hostname issue.

To resolve this issue, you can usemysqli_error()Use a function to obtain more information about a query failure. For example, you can add the following code tomysqli_query()later:

$result = mysqli_query($conn, $query);
if (!$result) {
    echo "查询失败: " . mysqli_error($conn);
}

This code will check.$resultIs it?falseIf so, output an error message indicating the reason for the failure.

You can also perform an error check before executing a query to ensure that both the connection and the query were successful. For example:

$conn = mysqli_connect($host, $user, $pass, $dbname);
if (!$conn) {
    die("连接数据库失败: " . mysqli_connect_error());
}

$query = "SELECT * FROM users";
$result = mysqli_query($conn, $query);
if (!$result) {
    die("查询失败: " . mysqli_error($conn));
}

This code first checks whether the connection was successful; if not, it outputs a connection error message and exits the program. Then, it executes the query and checks whether the result isfalseIf so, output an error message and exit the program.

Please note that the above code is for illustrative purposes only and may require modification or improvement in actual deployment. Additionally, if you are handling sensitive data—such as user information or payment details—please ensure that appropriate security measures are implemented to protect this data.