无法从数据库中获取数据（PDO SQLSTATE [HY000]：一般错误，请提问）

Question

我使用PHP执行SQL语句，但它返回“ PDO SQLSTATE [HY000]：常规错误”，但在“ phpMyAdmin”中有效，并且返回了我想要的结果。

这是我的代码，只是一个示例（可能包含一些错字）

try{
    $query = $con->prepare("
        set @pointA = (
            SELECT tc.sort FROM tableC tc
            INNER JOIN tableT tt ON tt.low = tc.id
            WHERE tt.id = :this
        );
        set @pointB = (
             SELECT tc.sort FROM tableC tc
             INNER JOIN tableT tt ON tt.high = tc.id
             WHERE tt.id = :this
        );
        set @main = (
            SELECT tl.id FROM tableT tt
            INNER JOIN tableC tcl ON tcl.id = tt.low
            INNER JOIN tableC tch ON tch.id = tt.high
            INNER JOIN tableL tl ON tch.pro= tl.id AND tcl.pro = tl.id
            WHERE tt.id = :this
        );
        set @min = (
           SELECT MIN(stage) FROM tableS
           WHERE ((stage >= @pointA AND stage <= @pointB) AND status = 1)
        );
        set @max = (
            SELECT MAX(stage) FROM tableS
            WHERE ((stage >= @pointA AND stage <= @pointB) AND status = 1)
        );
        set @pointD = (
            SELECT td.time FROM tableT tt
            INNER JOIN tableD td ON td.pro = tt.id
            WHERE tt.low = @pointA AND td.main = 1
        );

        SELECT @pointD AS DropPoint,@main AS MainProd, @min AS min, @max AS max,@pointA AS StartPoint,@pointB AS EndPoint,ts.type,ps.type AS typename,tf.price FROM tableS ts
        INNER JOIN point_type pt ON pt.id = ts.type
        INNER JOIN point_cost pc ON pc.pro = :this AND pc.type = ts.type 
        AND pc.layer = :layer
        WHERE ts.no = :no and ts.main = @main
    ")
    $query->bindParam(':no',$no);
    $query->bindValue(':this',encode($target));
    $query->bindParam(':layer',$random);
    $query->execute();
    while($x=$query->fetch(PDO::FETCH_ASSOC)){
        //.......
    }
}
catch(PDOException $x){
    echo $x->getMessage();
}

我尝试在return false;之后添加$query->execute();，但没有返回任何错误，是fetch(PDO::FETCH_ASSOC)造成的问题吗？