c# - SCOPE_IDENTITY() 总是返回 0

Question

我的存储过程是:

ALTER PROCEDURE [dbo].[Insert_QuickLabDump]
    @Specimen_ID [varchar](50),
    @Client_Key int,
    @Outcome [varchar](50),
    @Medications [varchar] (max),
    @Date_Collected date,
@Time_Collected time(0) ,
@Date_Entered date,
@Time_Entered time(0) ,
@Date_Completed date,
@Time_Completed time(0) ,
@Test_Date date ,
@Test_Time time(0) ,

    @Practice_Name [varchar] (500),
    @Practice_Code [varchar] (500),
    @Client_ID [varchar] (500),
    @Requesting_Physician [varchar] (500),
    @Other_Medications [varchar] (max),
    @Order_Comments [varchar] (max),
    @Reference_Number [varchar] (500),
    @Order_Count int,
    @lastrecord INT OUTPUT

AS
BEGIN
    -- SET NOCOUNT ON added to prevent extra result sets from
    -- interfering with SELECT statements.
    SET NOCOUNT ON;

    INSERT INTO [SalesDWH].[dbo].[QuickLabDump]
           ([Specimen ID]
           ,[Client Key]
           ,[Outcome]
           ,[Medications]
           ,[Date Collected],
[Time Collected]  ,[Date Entered] ,
[Time Entered]  ,
[Date Completed] ,
[Time Completed]  ,
[Test Date]  ,
[Test Time]  ,


           [Practice Name]
           ,[Practice Code]
           ,[Client ID]
           ,[Requesting Physician]
           ,[Other Medications]
           ,[Order Comments]
           ,[Reference Number]
           ,[Order Count])
     VALUES
           (@Specimen_ID,
@Client_Key,
@Outcome,
@Medications,
@Date_Collected ,
@Time_Collected ,
@Date_Entered,
@Time_Entered ,
@Date_Completed ,
@Time_Completed,
@Test_Date ,
@Test_Time,
@Practice_Name,
@Practice_Code,
@Client_ID,
@Requesting_Physician,
@Other_Medications,
@Order_Comments,
@Reference_Number,
@Order_Count
);
    select @lastrecord = scope_identity();
END

出于某种原因，它每次都返回 0。

我是这样执行的:

public static int Insert_QuickLabDump(QuickLabDump dump)
{
   try
   {
      DbConnection cn = GetConnection2();
      cn.Open();

      // stored procedure
      DbCommand cmd = GetStoredProcCommand(cn, "Insert_QuickLabDump");
      DbParameter param;

      param = CreateInParameter("Specimen_ID", DbType.String);
      param.Value = dump.Specimen_ID;
      cmd.Parameters.Add(param);

       ..... (lots more parameters - same method) ......

       param = CreateOutParameter("lastrecord", DbType.Int32);

       cmd.Parameters.Add(param);

       // execute
       int id=cmd.ExecuteScalar().ToInt();
       return id;

       if (cn.State == ConnectionState.Open)
           cn.Close();
   }
   catch (Exception e)
   {
      throw e;
   }
}

我做错了什么？

Answer 1

看起来您正在使用 ExecuteScalar() 而不是查看输出参数来获取标识。执行后查看输出参数的值，或选择 SCOPE_IDENTITY() 作为查询结果。

这是一个应该与 ExecuteScalar() 一起使用的简单示例:

CREATE PROCEDURE dbo.QuickExample

    @Name VARCHAR( 50 )

AS

INSERT INTO dbo.MyTable( Name )
    VALUES( @Name );

SELECT SCOPE_IDENTITY();

GO

以下是创建带有输出参数的存储过程的方法:

CREATE PROCEDURE dbo.QuickExample

    @Name   VARCHAR( 50 ),
    @Id INT OUTPUT

AS

INSERT INTO dbo.MyTable( Name )
    VALUES( @Name );

SET @Id = SCOPE_IDENTITY();

GO

如果使用输出参数，则在调用存储过程时必须将其指定为一个。调用存储过程后，参数将填充存储过程中设置的值。