Question

我一直在努力处理下面的剧本，我无法找到更好的方法来做到这一点有谁看到这个问题？我正确地声明了变量。为什么失败了？谢谢你的帮助！

DECLARE @var1 as VarChar(50) 
DECLARE @var2 as VarChar(50) 

SET @Var1 = '1, 2, 3, 4, 5'

EXEC('IF (select count(*) from Table1 where Column1 in (' + @Var1 + ')) = 5 
     SET @Var2 = ''True''
ELSE 
     SET @Var2 = ''False''')

SELECT @Var2

错误讯息：

必须声明SCALAR VARIABLE @ Var2

Answer 1

如果您想从参数中获取值，则需要使用sp_executesql。

要缩短查询，请使用CASE。

DECLARE @var1 as VarChar(50) 
DECLARE @var2 as VarChar(50) 
SET @Var1 = '1, 2, 3, 4, 5'
SET @sqlCommand = 'SELECT @Var = CASE WHEN count(*) = 5 THEN ''TRUE'' ELSE ''FALSE'' END FROM Table1 where Column1 IN (' + @Var1 + ')'
EXECUTE sp_executesql @sqlCommand, N'@Var VARCHAR(5) OUTPUT', @Var=@var2 OUTPUT
SELECT @Var2

如果您想知道桌面上是否存在ID的所有@Var1，您还需要使用DISTINCT

SET @sqlCommand = 'SELECT @Var = CASE WHEN count(DISTINCT Column1) = 5 THEN ''TRUE'' ELSE ''FALSE'' END FROM Table1 where Column1 IN (' + @Var1 + ')'

sp_executesql ^{MSDN Docs}

Answer 2

因为exec正在执行单引号内的SQL的动态部分。但是@ var2是在exec之外声明的。要解决此问题并在exec中选择@ var2或使用@ var2作为设置'+ @ var2 +'

Answer 3

使用sp_executeSQL而不是exec并使用输出参数

E.g。 How to get sp_executesql result into a variable?

例如

DECLARE @var1 as VarChar(50) 
DECLARE @var2 as VarChar(50) 
DECLARE @ParmDefinition nvarchar(500);
SET @Var1 = '1, 2, 3, 4, 5'

SET @ParmDefinition = N'@Var2  VarChar(50) OUTPUT';

DECLARE @sSQL nvarchar(500);

set @sSQL =  'IF (select count(*) from Table1 where Column1 in (' + @Var1 + ')) = 5 
     SET @Var2 = ''True''
ELSE 
     SET @Var2 = ''False'''

EXEC sp_executesql @sSQL, @ParmDefinition, @Var2=@Var2 OUTPUT;

SELECT @Var2;

Answer 4

那里有两件事......首先是“;”结束句子。您还需要scape varchar值。

同意其他答案...使用sp_executeSQL运行动态sql。

宣告的一个例子......

USE AdventureWorks2012;
GO
DECLARE @find varchar(30); 
/* Also allowed: 
DECLARE @find varchar(30) = 'Man%'; 
*/
SET @find = 'Man%'; 
SELECT p.LastName, p.FirstName, ph.PhoneNumber
FROM Person.Person AS p 
JOIN Person.PersonPhone AS ph ON p.BusinessEntityID = ph.BusinessEntityID
WHERE LastName LIKE @find;

sp_executeSQL的一个例子..

DECLARE @IntVariable int;
DECLARE @SQLString nvarchar(500);
DECLARE @ParmDefinition nvarchar(500);

/* Build the SQL string one time.*/
SET @SQLString =
     N'SELECT EmployeeID, NationalIDNumber, Title, ManagerID
       FROM AdventureWorks.HumanResources.Employee 
       WHERE ManagerID = @ManagerID';
SET @ParmDefinition = N'@ManagerID tinyint';
/* Execute the string with the first parameter value. */
SET @IntVariable = 197;
EXECUTE sp_executesql @SQLString, @ParmDefinition,
                      @ManagerID = @IntVariable;
/* Execute the same string with the second parameter value. */
SET @IntVariable = 109;
EXECUTE sp_executesql @SQLString, @ParmDefinition,
                      @ManagerID = @IntVariable;

Answer 5

有许多理由不让执行sql字符串。我会改写这个：

declare @cnt int

select @cnt = count(1) 
from Table1 
where Column1 in
    (select items
    from dbo.Split(@Var1,',')
    )

return @cnt   -- then the calling function says if this is true or false.

对于Split函数，请参阅：HERE

为什么EXEC会报告必须DECLARE SCALAR VARIABLE的错误

5 个答案: