Question

如果我有以下存储过程，如何在代码中调用所选值，即CourseId，以便将其设置为变量？

CREATE PROCEDURE [dbo].GetCourseIDFromCourseNumber(
 @courseNo int,
 @termId int,
 @courseId int OUTPUT
)
AS
BEGIN

SELECT @courseId = CourseId
FROM Course
Where (CourseNumber = @courseNo AND TermId = @termId)

END

C＃代码

   objCommand.CommandType = CommandType.StoredProcedure;
            objCommand.CommandText = "GetCourseIDFromCourseNumber";

            objCommand.Parameters.AddWithValue("@courseNo", courseNumber);
            objCommand.Parameters.AddWithValue("@termId", term);
            objCommand.Parameters.AddWithValue("@section", section);

            //Create an Output parameter to store value from stored procedure
            SqlParameter courseIdParam = new SqlParameter("@courseId", SqlDbType.Int);
            courseIdParam.Direction = ParameterDirection.Output;
            objCommand.Parameters.Add(courseIdParam);

            //execute stored procedure
            DBConnect objDB = new DBConnect();
            SqlConnection connect = objDB.GetConnection();
            connect.Open();                                                   
            objCommand.ExecuteNonQuery();
            connect.Close();

            //read parameter value
            if (courseIdParam.Value != null)
            {
                var courseId = (int)courseIdParam.Value;
                Session["Course"] = courseId;
            }

GetDataSet方法

public DataSet GetDataSetUsingCmdObj(SqlCommand theCommand)
{
        // Used for stored procedures (Select only) with parameters
        try
        {
            theCommand.Connection = myConnectionSql;
            SqlDataAdapter myDataAdapter = new SqlDataAdapter(theCommand);

            DataSet myDataSet = new DataSet();
            myDataAdapter.Fill(myDataSet);

            ds = myDataSet;
        }
        catch (Exception e)
        {
        }
        finally
        {
            myConnectionSql.Close();
        }

        return ds;
    }

Answer 1

创建FUNCTION而不是存储过程：

CREATE FUNCTION [dbo].GetCourseIDFromCourseNumber(
@courseNo int,
@termId int
)
RETURNS TABLE
AS RETURN
(
    SELECT CourseId
    FROM Course
    Where (CourseNumber = @courseNo AND TermId = @termId)
)

您现在可以在任何查询中使用输出，例如：

SELECT CourseId
FROM dbo.GetCourseIDFromCourseNumber(123,1);

SELECT t.*
FROM myTable t
CROSS APPLY dbo.GetCourseIDFromCourseNumber(123,1) c
WHERE t.CourseId = c.CourseId

Answer 2

我个人喜欢将存储过程中返回的值存储到DataTable而不是DataSet中;然而，在这种情况下，这完全是个人偏好。然后，您需要遍历DataTable行中的数据。

请参阅以下代码：

string courseId;

DataTable myDataTable = new DataTable();
myDataAdapter.Fill(myDataTable);

foreach (DataRow dr in dt.Rows)
{
     courseId = dr["CourseId"].ToString();
}

Answer 3

由于海报添加了相关的C＃代码，因此很明显存储过程可能是合适的。

如果存储过程只返回一个值（而不是数据集），那么最好将该值作为OUTPUT参数返回：

CREATE PROCEDURE [dbo].GetCourseIDFromCourseNumber(
@courseNo int,
@termId int,
@courseId int OUTPUT
)
AS
BEGIN

    SELECT @courseId = CourseId
    FROM Course
    Where (CourseNumber = @courseNo AND TermId = @termId)

END

现在在C＃中：

SqlCommand objCommand = new SqlCommand();
objCommand.CommandType = CommandType.StoredProcedure;
objCommand.CommandText = "GetCourseIDFromCourseNumber";

objCommand.Parameters.AddWithValue("@courseNo", courseNumber);
objCommand.Parameters.AddWithValue("@termId", term);

// Create an OUTPUT parameter to store value from stored procedure
SqlParameter courseIdParam = new SqlParameter("@courseId", SqlDbType.Int);
courseIdParam.Direction = ParameterDirection.Output;
objCommand.Parameters.Add(courseIdParam);

// Execute stored procedure
objCommand.ExecuteNonQuery();

// Read parameter value
if(courseIdParam.Value != null)
{
    var courseId = (int)courseIdParam.Value;
}

如何从存储过程调用选定的值

3 个答案: