PHP上mySQL上的SQL语法错误

Question

I have a query that I have to execute and when I execute it in mySql Workbench it works fine but when I put it in together with php I get error:

You have an error in your SQL syntax;

this is the code:

$usr=$_POST['username'];
$link=mysqli_connect("$host", "$username", "$password","$db_name")or die("cannot connect");
if(!$link)
{
    echo 'no connection';
}
else
{
    //the query
    $query="SET @userId:=(SELECT memberId FROM members WHERE  username='$usr');
                SELECT u FROM Status WHERE members_memberId=@userId";
    $result=mysqli_query($link,$query);
    if(!$result)
    {
        $error=mysqli_error($link);
        echo 'error '.$error;
    }
    else
    {
        if($result->num_rows>0)
        {
            while($row=$result->fetch_assoc())
            {
                echo $row['u'];

            }
        }
    }

Answer 1

You are trying to execute multiple query using the function mysqli_query . For executing multi-query the function is multi_query

In the current context you can do with 2 queries as

$query1="SET @userId:=(SELECT memberId FROM members WHERE  username='$usr')";
$query2 = "SELECT u FROM Status WHERE members_memberId=@userId";

mysqli_query($link,$query1);
$result= mysqli_query($link,$query2);