error in your SQL syntax; check the manual that corresponds to your MySQL server

This error message is indicating that there is a problem with the SQL syntax used in the query. It suggests checking the manual for the correct syntax to use with the version of MySQL that is running on the server. The specific issue with the syntax needs to be identified and corrected in order to resolve the error.

Here's an example to help you understand it better:

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<?php

// Connect to the MySQL database server
$mysql_host = "localhost";
$mysql_username = "root";
$mysql_password = "secret";
$mysql_database = "test_db";

$conn = mysqli_connect($mysql_host, $mysql_username, $mysql_password, $mysql_database);

// Check if the connection was successful
if (!$conn) {
    die("Connection failed: " . mysqli_connect_error());
}

// Define an incorrect SQL query
$sql = "SELECT * FROM non_existent_table";

// Execute the query
$result = mysqli_query($conn, $sql);

// Check if the query failed
if (!$result) {
    // Get the error message
    $error = mysqli_error($conn);

    // Print the error message
    echo "Error in your SQL syntax: " . $error;
} else {
    // Fetch the result data
    while ($row = mysqli_fetch_assoc($result)) {
        print_r($row);
    }
}

// Close the database connection
mysqli_close($conn);

?>