Question

我有这个查询，我正在通过选择查询在表中插入日期。

INSERT INTO TEST
SELECT * FROM (SELECT myDate, EmpCode, '2020-04-11 09:10:21', '2020-04-11 18:47:56') TBL
WHERE NOT EXISTS (SELECT * FROM TEST WHERE myDate = TBL.myDate AND EmpCode = TBL.EmpCode)

此查询可能生成的日期为

Date          EmpCode  Check In               Check Out
2020-04-11    101      2020-04-11 09:10:21    2020-04-11 18:47:56

因此，如果我尝试添加相同的记录，它将不会添加到TEST表中，但是如果我更改值，它将被添加。假设EmpCode是101，而myDate是GETDATE()。现在，对于同一日期和同一员工，如果我更改任何列的值，那么这里的第一个datetime是Check In，第二个是Check Out，所以如果我将Check Out更新为{{1 }}，我不想在表中插入任何行，而是用新值更新现有行。我应该做些什么来使这项工作。用更新后的值执行查询后的输出应该是

'2020-04-11 18:19:32'

Answer 1

我认为您正在寻找MERGE声明。

MERGE TEST AS TARGET
    USING (SELECT myDate, EmpCode, '2020-04-11 09:10:21' AS check_in, '2020-04-11 18:47:56' AS check_out) AS SOURCE
-- Replace it with with actual source query. this is just an exmaple.
ON TARGET.EmpCode = SOURCE.EmpCode
AND TARGET.myDate = SOURCE.myDate
WHEN MATCHED
    THEN UPDATE SET 
        check_in = SOURCE.check_in
        , check_out = SOURCE.check_out
WHEN NOT MATCHED BY TARGET 
    THEN INSERT (myDate, EmpCode, check_in, check_out)
         VALUES (SOURCE.myDate, SOURCE.EmpCode, SOURCE.check_in, SOURCE.check_out);

您可以从here或official doc探索有关MERGE的更多信息。

如何更新插入选择查询中的记录

1 个答案: