将id相同的B表的name更新到A表
表a 字段id name 表b id name
1 aa 1 aa
2 bb 2 kk
3 cc 3 mm
4 ll
UPDATE a t
SET name = (SELECT name FROM b WHERE ID = t.ID)
WHERE EXISTS (SELECT 1 FROM b WHERE ID = t.ID AND name != t.name)
更新后A的结果
1 aa
2 kk
3 mm
4 ll
将id相同的B表的name更新到A表
表a 字段id name 表b id name
1 aa 1 aa
2 bb 2 kk
3 cc 3 mm
4 ll
UPDATE a t
SET name = (SELECT name FROM b WHERE ID = t.ID)
WHERE EXISTS (SELECT 1 FROM b WHERE ID = t.ID AND name != t.name)
更新后A的结果
1 aa
2 kk
3 mm
4 ll