MERGE

Question

我主要使用 mySQL 所以转移到 azure 和 sql 服务器我意识到在重复上不起作用。

我正在尝试这样做：

INSERT INTO records (jid, pair, interval, entry) VALUES (1, 'alpha', 3, 'unlimited') ON DUPLICATE KEY UPDATE entry = "limited";

但是这里当然不允许重复键。所以 MERGE 是正确的形式。

我看过： https://technet.microsoft.com/en-gb/library/bb522522(v=sql.105).aspx

但老实说，这个例子有点过分，让人流口水。有人可以为我简化它以适合我的示例以便我更好地理解它吗？

Answer 1

为了进行合并，您需要某种形式的源 table/table var 用于合并语句。然后你可以进行合并。所以可能是这样的（注意：没有完全检查语法，提前道歉）：

WITH src AS (
    -- This should be your source
    SELECT 1 AS Id, 2 AS Val
)
-- The above is not neccessary if you have a source table
MERGE Target -- the detination table, so in your case records
USING src -- as defined above
ON (Target.Id = src.Id) -- how do we join the tables
WHEN NOT MATCHED BY TARGET 
    -- if we dont match, what do to the destination table. This case insert it.
    THEN INSERT(Id, Val) VALUES(src.Id, src.Val)
WHEN MATCHED 
    -- what do we do if we match. This case update Val
    THEN UPDATE SET Target.Val = src.Val;

不要忘记阅读正确的语法页面：https://msdn.microsoft.com/en-us/library/bb510625.aspx

我认为这可以转化为您的示例 (tm)：

WITH src AS (
    -- This should be your source
    SELECT 1 AS jid, 'alpha' AS pair, 3 as 'interval'
)
MERGE records -- the detination table, so in your case records
USING src -- as defined above
ON (records.Id = src.Id) -- how do we join the tables
WHEN NOT MATCHED BY TARGET 
    -- if we dont match, what do to the destination table. This case insert it.
    THEN INSERT(jid, pair, interval, entry) VALUES(src.jid, src.pair, src.interval, 'unlimited')
WHEN MATCHED 
    -- what do we do if we match. This case update Val
    THEN UPDATE SET records.entry = 'limited';

MERGE - 用 sql 服务器替换 ON Duplicate

MERGE - to replace ON Duplicate with sql server

sql

sql-server

azure