用于合并集合的更好的T-SQL解决方案?
给定以下数据/模式:用于合并集合的更好的T-SQL解决方案?,sql,sql-server,tsql,Sql,Sql Server,Tsql,给定以下数据/模式: DECLARE @t1 TABLE ( Id int NOT NULL ) DECLARE @t2 TABLE ( Id INT NOT NULL, Val1 CHAR(1) NOT NULL ) DECLARE @t3 TABLE ( Id INT NOT NULL, Val2 CHAR(1) NOT NULL ) INSERT INTO @t1 VALUES (1) INSERT INTO @t2 VALUES (1, 'A
DECLARE @t1 TABLE (
Id int NOT NULL
)
DECLARE @t2 TABLE (
Id INT NOT NULL,
Val1 CHAR(1) NOT NULL
)
DECLARE @t3 TABLE (
Id INT NOT NULL,
Val2 CHAR(1) NOT NULL
)
INSERT INTO @t1 VALUES (1)
INSERT INTO @t2 VALUES (1, 'A')
INSERT INTO @t2 VALUES (1, 'B')
INSERT INTO @t2 VALUES (1, 'C')
INSERT INTO @t3 VALUES (1, '9')
INSERT INTO @t3 VALUES (1, '8')
我希望看到以下结果集:
Id,Val1,Val2
1,'A','9'
1,'B','8'
1,'C',NULL
现在添加以下内容:
INSERT INTO @t3 VALUES (1, '7')
INSERT INTO @t3 VALUES (1, '6')
我想看看这个:
Id,Val1,Val2
1,'A','9'
1,'B','8'
1,'C','7'
1,NULL,'6'
以下是我的想法:
DECLARE @t4 TABLE(
Id INT NOT NULL,
RowNumber INT NOT NULL,
Val1 CHAR(1) NULL,
Val2 CHAR(1) NULL
)
INSERT INTO @t4 (Id, RowNumber, Val1)
SELECT Id, ROW_NUMBER() OVER(ORDER BY Id), Val1
FROM @t2
MERGE @t4 T
USING(SELECT Id, ROW_NUMBER() OVER(ORDER BY Id) RowNumber, Val2 FROM @t3) S
ON (T.Id = S.Id AND T.RowNumber = S.RowNumber)
WHEN MATCHED THEN
UPDATE SET T.Val2 = S.Val2
WHEN NOT MATCHED THEN
INSERT (Id, RowNumber, Val2) VALUES (Id, RowNumber, Val2);
SELECT Id, Val1, Val2 FROM @t4
但我想知道是否有人能想出更简单的方法,使用SELECT with JOIN代替MERGE
ROW_NUMBER()OVER(ORDER BY Id)
在出现领带时是不确定的。没有具体的结果是可以保证的。所以9
也可以与B
@MartinSmith配对,这很好。我不在乎这个案子的顺序
;with q2 as (
select
Id,
Val1,
ROW_NUMBER() OVER(ORDER BY Val1) rn
from @t2
), q3 as (
select
Id,
Val2,
ROW_NUMBER() OVER(ORDER BY Val2 DESC) rn
from @t3
)
select
isnull(q2.Id, q3.Id) as Id,
q2.Val1,
q3.Val2
from
q2 full outer join
q3 on q2.Id = q3.Id and q2.rn = q3.rn