为什么输出参数在c#级别返回0

本文关键字：返回 输出 参数 为什么 | 更新日期: 2023-09-27 18:16:23

我试图从存储过程中获得输出，但在c#中它给了我0。

 public short SelectOccupantTypesByOccupantTypeID(Int64 OccupantID)
            {
                SqlCommand SqlCom = new SqlCommand("SelectOccupantTypesByOccupantTypeID", DatabaseConnection.OpenConnection());
                SqlCom.CommandType = CommandType.StoredProcedure;
                SqlCom.Parameters.AddWithValue("@pk_Occupants_OccupantID", OccupantID);
                SqlParameter sqlParamOccupantTypeID = new SqlParameter("@OccupantTypeID", SqlDbType.SmallInt);
                sqlParamOccupantTypeID.Direction = ParameterDirection.Output;
                SqlCom.Parameters.Add(sqlParamOccupantTypeID);
                short OccupantTypeID = Convert.ToInt16(sqlParamOccupantTypeID.Value);
                SqlCom.ExecuteNonQuery();
                DatabaseConnection.CloseConnection();
                return OccupantTypeID;
            }

试图得到它

protected void ddlOccupants_SelectedIndexChanged(object sender, EventArgs e)
    {
        Int64 OccupantID= Convert.ToInt64(ddlOccupants.SelectedValue);
        Int16 OccupantTypeID= MngOccupants.SelectOccupantTypesByOccupantTypeID(OccupantID);
        txtBoxMonthlyInstallment.Text = OccupantTypeID.ToString();
    }

SP: 

alter PROCEDURE [dbo].[SelectOccupantTypesByOccupantTypeID] 
    @pk_Occupants_OccupantID bigint,
    @OccupantTypeID smallint output
AS
BEGIN
         Set @OccupantTypeID= (Select Occupants.OccupantsOccupantTypeID 
         From Occupants
         Where Occupants.pk_Occupants_OccupantID= @pk_Occupants_OccupantID)
         return @OccupantTypeID
END

但是sp在sql级别返回正确的值，但在c#级别返回0。为什么?

为什么输出参数在c#级别返回0

在执行查询之前正在读取参数的值，请交换顺序。

SqlCom.ExecuteNonQuery();
short OccupantTypeID = Convert.ToInt16(sqlParamOccupantTypeID.Value);

不管你犯了什么"坏习惯"，你的连接真的应该被包装在using语句中，而不是在你的程序中重用。ADO。. NET已经实现了连接池，您不需要自己做，只需根据需要创建短暂的连接，当您处置它们时，它们将返回到池中。

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