Question

我们用于CrystalReport的这个T-SQL查询。

SELECT COUNT(*) AS Expr1, [Date], StoreNumber
FROM   dbo.Orderp
WHERE  (OpServerNumber = 0)
GROUP BY [Date], StoreNumber

如果没有行对特定日期和商店有效，则会出现问题。

如果查询找不到表中的任何行，是否可以返回Expr1 = 0的单行？

Answer 1

如果您想要至少一行，则可以使用EXISTS条件：

IF EXISTS(SELECT COUNT(*) AS Expr1, [Date], StoreNumber FROM   dbo.Orderp WHERE  (OpServerNumber = 0) GROUP BY [Date], StoreNumber)
    SELECT COUNT(*) AS Expr1, [Date], StoreNumber FROM   dbo.Orderp WHERE  (OpServerNumber = 0) GROUP BY [Date], StoreNumber
ELSE
    SELECT 0 AS Expr1, NULL [Date], 0 StoreNumber

Answer 2

如果您将此封装在存储过程中，则可以：

将这些行选择为表变量或临时表
检查@@ROWCOUNT，如果是IF @@ROWCOUNT = 0，则明确向该临时表添加虚拟行
作为存储过程

SELECT * FROM .....

Answer 3

问题是你在单一选择中使用count（*）和其他列。

如果

查询满足where子句，它将至少获得一行。

您需要将count（*）和仅列查询分开。

Answer 4

SELECT 
    COUNT(*) AS Expr1, [Date], StoreNumber 
FROM dbo.Orderp WHERE  (OpServerNumber = 0) GROUP BY [Date], StoreNumber

if @@ROWCOUNT = 0
    SELECT 0 AS Expr1, NULL [Date], 0 StoreNumber

Answer 5

select Expr1, [Date], StoreNumber from (
    select *,row_number() over (order by isrealrow desc) rownum from (
        select COUNT(*) as Expr1,[Date], StoreNumber, 1 as isrealRow FROM  dbo.Orderp
        WHERE  (OpServerNumber = 0)
        GROUP BY [Date], StoreNumber
        union
        select 0, NULL, NULL, 0 as isrealrow 
    ) b
)c
where isrealRow=1 or rownum=1

这是我整天写的最酷的SQL。

Answer 6

SELECT ISNULL(B.num,0) AS Expr1, A.[Date], A.StoreNumber
FROM 
(SELECT [Date], StoreNumber FROM dbo.Orderp GROUP BY [Date], StoreNumber) A
LEFT OUTER JOIN
(SELECT COUNT(*) AS num, [Date], StoreNumber
FROM   dbo.Orderp
WHERE  (OpServerNumber = 0)
GROUP BY 
[Date], StoreNumber) B ON A.[Date]=B.[Date] AND A.StoreNumber=B.StoreNumber

编辑：我只是想到了另一个......

SELECT
SUM(Expr1) AS Expr1, [Date], StoreNumber
FROM
(SELECT 0 AS Expr1, [Date], StoreNumber, NULL AS OpServerNumber
FROM   dbo.Orderp
GROUP BY [Date], StoreNumber
UNION ALL
SELECT 1, [Date], StoreNumber, OpServerNumber
FROM   dbo.Orderp)T
WHERE OpServerNumber IS NULL OR OpServerNumber = 0
GROUP BY [Date], StoreNumber

如果没有找到行，则返回单行

6 个答案: