Question

我正在尝试使用merge语句通过连接另外两个表来更新一个表。我写的更新语句非常慢，所以我想用合并替换它。这是剧本给我带来的问题。

UPDATE T1 
SET TitleID = T2.TitleID 
FROM Customer T1 
INNER JOIN Customer_Temp T3 
    on T1.importFK = T3.importFK 
INNER JOIN Customer_Title T2 
    on T2.TitleDescription = T3.TitleDescription 
    and T2.ID = @ID

Answer 1

MERGE可能不会提高性能。对于此查询：

UPDATE T1 
    SET TitleID = T2.TitleID 
    FROM Customer T1 INNER JOIN
         Customer_Temp T3 
         ON T1.importFK = T3.importFK INNER JOIN
         Customer_Title T2 
         ON T2.TitleDescription = T3.TitleDescription AND T2.ID = @ID;

你想要索引。我建议：

Customer_Title(ID, TitleDescription, TitleId)
Customer_Temp(TitleDescription, importFK)
Customer(importFK)

通过加入其他2人合并到一张桌子

1 个答案: