SQLSERVER链接服务查询快，更新慢问题(未能创建可接受的游标后续)

CREATE TABLE #t1
(
id INT IDENTITY(1, 1)
NOT NULL ,
BH INT
)
INSERT INTO #t1
SELECT 492417420
SELECT *
FROM #t1

DROP TABLE #t1

--更新一条数据 ，实际上更新影响0行
--4秒
UPDATE test.[sgoa_data].[dbo].[nsb]
SET flag = 1 FROM
test.[sgoa_data].[dbo].[nsb] AS a JOIN (SELECT B.bh FROM test.[sgoa_data].[dbo].[nsb] AS B ,
#t1 AS C
WHERE B.bh = C.bh) E
ON a.bh = E.bh

--25秒
UPDATE test.[sgoa_data].[dbo].[nsb]
SET flag = 1 FROM
test.[sgoa_data].[dbo].[nsb] AS a ,
#t1 AS b
WHERE a.bh = b.bh

SELECT A.* FROM test.[sgoa_data].[dbo].[nsb] AS a JOIN (SELECT B.* FROM test.[sgoa_data].[dbo].[nsb] AS B ,
#t1 AS C
WHERE B.bh = C.bh) E

ON a.bh = E.bh

问题处理

--0秒

UPDATE a
SET flag = 1
FROM LINK_39.SGOA_DATA.dbo.NSB AS a
JOIN ( SELECT DISTINCT
b.bh
FROM LINK_39.SGOA_DATA.dbo.NSB AS B ,
#t1 AS C
WHERE B.bh = C.bh
) E ON a.bh = E.bh