T-SQL: How to use parameters in dynamic SQL?

问题:

I have the following dynamic query which is working fine without the WHERE clause, which is expecting UNIQUEIDENTIFIER.

When I pass it in, I don't get a result. I tried CAST and CONVERT, but no result. I might be doing it wrong, can anybody help?

CREATE PROCEDURE [dbo].[sp_Test1] /* 'b0da56dc-fc73-4c0e-85f7-541e3e8f249d' */
(
@p_CreatedBy UNIQUEIDENTIFIER
)
AS
DECLARE @sql NVARCHAR(4000)
SET @sql ='

DECLARE @p_CreatedBY UNIQUEIDENTIFIER

SELECT 
  DateTime,
  Subject,
  CreatedBy
FROM
(
  SELECT 
    DateTime, Subject, CreatedBy, 
    ROW_NUMBER() OVER(ORDER BY DateTime ) AS Indexing
  FROM
    ComposeMail
  WHERE 
    CreatedBy = @p_CreatedBy /* <--- the problem is in this condition */
) AS NewDataTable
'

EXEC sp_executesql @sql

回答1:

You must pass in the parameters to sp_executesql. See MSDN for details.

...
 WHERE 
    CreatedBy = @p
...

EXECUTE sp_executesql @sql, N'@p UNIQUEIDENTIFIER', @p = @p_CreatedBY

回答2:

DECLARE @ParmDefinition NVARCHAR(500)
SET @ParmDefinition = '@p_CreatedBy UNIQUEIDENTIFIER'

EXEC sp_executesql @sql, @ParmDefinition, @p_CreatedBy = @p_CreatedBy

回答3:

I'm not sure if your variable is getting populated in string format or binary, but you may need to quote the uniqueidentifier in your where clause. If you just select the uniqueidentifier field, does it come back as string or binary?

回答4:

Multiple parameter syntax. Maybe this will save someone an extra Google Search:

exec sp_executesql 
    @qry, 
    N'@value1 int, @value2 int, @currentValue int', 
    @value1 = @value1, @value2 = @value2, @currentValue = @currentValue