我有这种工作的DB2请求
MERGE INTO table_to_upsert AS tab
USING (VALUES
(1, 2, 3),
(4, 5, 6),
(7, 8, 9)
-- more rows
) AS merge (C1, C2, C3)
ON tab.key_to_match = merge.key_to_match -- usually the primary key example : tab.C2 = merge.C2
WHEN MATCHED THEN
UPDATE SET tab.C1 = merge.C1,
tab.C2 = merge.C2,
tab.C3 = merge.C3
WHEN NOT MATCHED THEN
INSERT (C1, C2, C3)
VALUES (merge.C1, merge.C2, merge.C3)
但是现在,我想要的是,如果主键已经存在,然后进行更新,但只有C1的新值与旧值不同时,才更新C1。
理论上是这样的
MERGE INTO table_to_upsert AS tab
USING (VALUES
(1, 2, 3),
(4, 5, 6),
(7, 8, 9)
-- more rows
) AS merge (C1, C2, C3)
ON tab.key_to_match = merge.key_to_match
WHEN MATCHED THEN
UPDATE SET tab.C1 = merge.C1,
tab.C2 = merge.C2,
tab.C3 = merge.C3
WHERE tab.C1 != merge.C1
WHEN NOT MATCHED THEN
INSERT (C1, C2, C3)
VALUES (merge.C1, merge.C2, merge.C3)
我添加,WHERE tab.C1 != merge.C1
但是它不起作用,导致
错误:非法符号在哪里;有效符号
如果我没记错的话,可以在匹配的行中添加一个搜索条件,即
MERGE INTO table_to_upsert AS tab
USING (VALUES
(1, 2, 3),
(4, 5, 6),
(7, 8, 9)
-- more rows
) AS merge (C1, C2, C3)
ON tab.key_to_match = merge.key_to_match
WHEN MATCHED AND tab.C1 != merge.C1 THEN
UPDATE SET tab.C1 = merge.C1,
tab.C2 = merge.C2,
tab.C3 = merge.C3
WHEN NOT MATCHED THEN
INSERT (C1, C2, C3)
VALUES (merge.C1, merge.C2, merge.C3)
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