sql性能优化实例

UPDATE mlxy 
SET mlxy.IsOwner = 1 
FROM
    mlxyUser mlxy WITH ( nolock )
    INNER JOIN v_Room2Customer vr2c WITH ( nolock ) ON mlxy.userid= vr2c.cardid
    INNER JOIN arean arean WITH ( nolock ) ON vr2c.areaname = arean.areaname 
    AND arean.areatype = '楼盘' 
    AND mlxy.UserID=@UserID;

UPDATE mlxy 
SET mlxy.IsOwner = 1 
FROM
    mlxyUser mlxy WITH ( nolock ) 
WHERE
    mlxy.UserId = @NewUserId 
    AND EXISTS (
    SELECT
        1 
    FROM
        v_Room2Customer vr2c WITH ( nolock )
        INNER JOIN arean WITH ( nolock ) ON vr2c.areaname = arean.areaname 
        AND arean.areatype = '楼盘' 
        AND mlxy.userid= vr2c.cardid 
    );