如何连接查询字符串

    $query="SELECT * FROM Table WHERE `id`=1 AND ";
    if(somecondition){
       $query .=" AND `ROUND(DATEDIFF(w.time_start, w.time_end) / 365.25)` >='".$data."'";
    }

我期望的是：当我使用 ' ' 时，它会连接起来。

SELECT * FROM Table WHERE `id`=1 AND `ROUND(DATEDIFF(w.time_start,w.time_end) / 365.25)`>='$data';