SQL Server MERGE，如果存在则更新else插入

Question

我有一个名为data的表ip, report_date, group, value其中包含列ip, report_date, group, value 。 主键是ip ， report_date和group在一起。

当表为空并且我运行下面的语句时，没有插入任何内容。 我的陈述有什么问题？

当匹配时，记录是按计划更新的...

MERGE bc_data2 AS Target
USING (SELECT ip, report_date, group, value FROM bc_data2 As b
WHERE b.ip = '1.1.1.2'
AND b.report_date = '2/29/2012'
AND b.group = 'EPO-Client-Update') AS Source
ON (Target.ip = Source.ip
AND Target.frequency = Source.frequency
AND Target.report_date = Source.report_date
AND Target.service = Source.service
AND Target.proxy_service = Source.proxy_service
AND Target.proxy = Source.proxy
AND Target.service_group = Source.service_group)
WHEN MATCHED THEN
    UPDATE SET Target.value = Target.value + 1
WHEN NOT MATCHED BY Target THEN
    INSERT (ip, report_date, group, value)
    VALUES ('1.1.1.2', '2/29/2012', 'EPO-Client-Update', 119437142);

Answer 1

您不添加任何行，因为您的using子句未返回任何行。 将常量放在带有列别名的using子句中，并使用when not matched的字段

像这样的东西有几个字段删除了简单性。

merge bc_data2 as T
using (select '1.1.1.2' as ip,
              '2012-02-29' as report_date,
              1194370142 as value) as S
on T.ip = S.ip and
   T.report_date = S.report_date
when matched then
  update set T.value = T.value + 1
when not matched then
  insert (ip, report_date, value) 
    values(ip, report_date, value);

Answer 2

我发现在MERGE语句的ON子句中NULLs不能很好地比较。 但是，将NULLs转换为空白是一种有效的解决方法。 我会修改ON语句看起来像这样。

ON (ISNULL(Target.ip, '')           = ISNULL(Source.ip, '')
AND ISNULL(Target.frequency, '')    = ISNULL(Source.frequency, '')
AND ISNULL(Target.report_date, '')  = ISNULL(Source.report_date, '')
AND ...)