假设我有一个包含复合主键的表:
create table FooBar (
fooId int not null,
barId int not null,
status varchar(20) not null,
lastModified datetime not null,
constraint PK_FooBar primary key (fooId, barId)
);
现在我有一些特定 fooId
的表格数据,可能是这样的:
1, 1, 'ACTIVE'
1, 2, 'INACTIVE'
...我想创建一个 MERGE 语句,将此表格数据视为权威 fooId
1,删除 中的所有不匹配记录FooBar
用于 fooId
1,但所有记录的 fooId
都不是 1。
例如,假设 FooBar
表当前有以下数据:
1, 1, 'ACTIVE', ... (some date, not typing it out)
2, 1, 'ACTIVE', ...
1, 3, 'INACTIVE', ...
2, 2, 'INACTIVE'
我想对上面提到的两个数据集运行合并语句,FooBar
中的结果数据集应该如下所示:
1, 1, 'ACTIVE', ...
2, 1, 'ACTIVE', ...
1, 2, 'INACTIVE', ...
2, 2, 'INACTIVE', ...
我希望删除 1, 3, 'INACTIVE'
行,并使用新修改的内容更新 1, 1, 'ACTIVE'
行时间戳,以及要插入的 1, 2, 'INACTIVE'
行。我还希望 2 的 fooId
的记录保持不变。
这可以在一条语句中完成吗?如果是,怎么办?
最佳答案
您可以使用 common table expressions对于您的目标和源,在这些 ctes 中,您可以应用过滤器来定义要使用的行:
-- t = Target = Destination Table = Mirror from Source
-- s = Source = New Data source to merge into Target table
declare @FooId int = 1;
;with t as (
select fooId, barId, [status], lastModified
from dbo.FooBar f
where f.fooId = @FooId
)
, s as (
select fooId, barId, [status], lastModified=sysutcdatetime()
from src
where src.fooId = @FooId
)
merge into t with (holdlock) -- holdlock hint for race conditions
using s
on (s.FooId = t.FooId and s.barId = t.barId)
/* If the records matches, update status and lastModified. */
when matched
then update set t.[status] = s.[status], t.lastModified = s.lastModified
/* If not matched in table, insert the record */
when not matched by target
then insert (fooId, barId, [status], lastModified)
values (s.fooId, s.barId, s.[status], s.lastModified)
/* If not matched by source, delete the record*/
when not matched by source
then delete
output $action, inserted.*, deleted.*;
rextester 演示:http://rextester.com/KRAI9699
返回:
+---------+-------+-------+----------+---------------------+-------+-------+----------+---------------------+
| $action | fooId | barId | status | lastModified | fooId | barId | status | lastModified |
+---------+-------+-------+----------+---------------------+-------+-------+----------+---------------------+
| INSERT | 1 | 2 | INACTIVE | 2017-09-06 16:21:21 | NULL | NULL | NULL | NULL |
| UPDATE | 1 | 1 | ACTIVE | 2017-09-06 16:21:21 | 1 | 1 | ACTIVE | 2017-09-06 16:21:21 |
| DELETE | NULL | NULL | NULL | NULL | 1 | 3 | INACTIVE | 2017-09-06 16:21:21 |
+---------+-------+-------+----------+---------------------+-------+-------+----------+---------------------+
合并
引用:
- Use Caution with SQL Server''s
MERGE
Statement - Aaron Bertrand - UPSERT Race Condition With
Merge
- Dan Guzman - An Interesting
MERGE
Bug - Paul White - Can I optimize this
merge
statement - Aaron Bertrand - If you are using indexed views and
MERGE
, please read this! - Aaron Bertrand - The Case of the Blocking
Merge
Statement (LCK_M_RS_U locks) - Kendra Little - Writing t-sql
merge
statements the right way - David Stein
关于sql-server - MERGE 与 DELETE 在目标上与源上的部分匹配?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/46079586/