如何在变量中存储固定行值-SQL server

我有一个表，最多可以有5行，最少可以有1行。现在我需要将这些行存储在不同的变量中，比如

@v1、@v2、@v3、@v4、@v5

。我怎么做

该表只有一列

custid

CustId
100
200
300
400

如果该表仅包含一行，则

@v1

应具有该值，其余可以为

null

尝试此操作

create table #tab
(
    custID int
)

insert into #tab
select 110 union all
select 120 union all
select 130 union all
select 140 union all
select 150

declare @v1 int,@v2 int, @v3 int, @v4 int, @v5 int

select @v1 = custID
from  #tab
order by custid 
OFFSET 0 row
FETCH  NEXT 1 ROW ONLY

select @v2 = custID
from  #tab
order by custid 
OFFSET 1 row
FETCH  NEXT 1 ROW ONLY

select @v3 = custID
from  #tab
order by custid 
OFFSET 2 row
FETCH  NEXT 1 ROW ONLY

select @v4 = custID
from  #tab
order by custid 
OFFSET 3 row
FETCH  NEXT 1 ROW ONLY


select @v5 = custID
from  #tab
order by custid 
OFFSET 4 row
FETCH  NEXT 1 ROW ONLY
select @v1,@v2,@v3,@v4,@v5

---

您可以使用以下查询：

SELECT @v1 = MAX(CASE WHEN rn = 1 THEN CustId END),
       @v2 = MAX(CASE WHEN rn = 2 THEN CustId END),
       @v3 = MAX(CASE WHEN rn = 3 THEN CustId END),
       @v4 = MAX(CASE WHEN rn = 4 THEN CustId END),
       @v5 = MAX(CASE WHEN rn = 5 THEN CustId END)
FROM (
   SELECT CustId, ROW_NUMBER() OVER (ORDER BY CustId) AS rn
   FROM mytable ) t

使用

ROW\u NUMBER

为表中的每条记录分配一个不同的编号。然后，在外部查询中使用条件聚合，您可以使用这个数字来设置每个单独的变量

如果少于5行，则相应的变量将设置为

NULL

---

如果您使用的是SQL Server 2012或更高版本，则可以尝试此功能

SELECT 
    @v1 = custID
  , @v2 = LAG(custID, 1) OVER (ORDER BY custID DESC)
  , @v3 = LAG(custID, 2) OVER (ORDER BY custID DESC)
  , @v4 = LAG(custID, 3) OVER (ORDER BY custID DESC)
  , @v5 = LAG(custID, 4) OVER (ORDER BY custID DESC)
FROM yourTable
ORDER BY CustID DESC

---

只是为了好玩，一个残酷的方法：

Select @v1 = t1.CustID,
       @v2 = oa2.CustID, 
       @v3 = oa3.CustID, 
       @v4 = oa4.CustID, 
       @v5 = oa5.CustID
from Table t1
outer apply(select top 1 CustID from Table t2 where t2.CustID not in(t1.CustID) order by CustID) oa2
outer apply(select top 1 CustID from Table t3 where t3.CustID not in(t1.CustID, oa2.CustID) Order by CustID) oa3
outer apply(select top 1 CustID from Table t4 where t4.CustID not in(t1.CustID, oa2.CustID, oa3.CustID) Order by CustID) oa4
outer apply(select top 1 CustID from Table t5 where t5.CustID not in(t1.CustID, oa2.CustID, oa3.CustID, oa4.CustID) Order by CustID) oa5

---

我们甚至可以使用PIVOT功能和帮助行数

declare @mytable  table  (CustId int)
insert into @mytable values
(100), (200), (300), (400),(500)


SELECT  [1] as V1, [2]as V2, [3]as V3, [4]as V4, [5]as V5
FROM
(SELECT CustId,ROW_NUMBER() OVER (ORDER BY CustId) AS value
    FROM @mytable ) AS SourceTable
PIVOT
(
max(CustId)
FOR value  IN ([1], [2], [3], [4],[5])
) AS PivotTable

这可能会有帮助。：）