我有一个不想跟踪的过程是创建还是更新。跟踪会很复杂。我想执行创建或更新。架构就像...
col1 varchar() (PK)
col2 varchar() (PK)
col3 varchar() (PK)
col4 varchar()
我正在考虑做
TRY
{
INSERT ...
}
CATCH(DuplicateKeyException)
{
UPDATE ...
}
你有什么建议?
我想确保我理解另一个投票最多的答案。给定我的模式,更新总是发生(即使有插入),但插入只发生在它不存在的地方?
//UPSERT
INSERT INTO [table]
SELECT [col1] = @col1, [col2] = @col2, [col3] = @col3, [col4] = @col4
FROM [table]
WHERE NOT EXISTS (
-- race condition risk here?
SELECT 1
FROM [table]
WHERE [col1] = @col1
AND [col2] = @col2
AND [col3] = @col3
)
UPDATE [table]
SET [col4] = @col4
WHERE [col1] = @col1
AND [col2] = @col2
AND [col3] = @col3