问在Convert.ToInt32(cmd.ExecuteScalar())中将数据类型nvarchar转换为int时出错

EN

Protected Sub btnCreateAudition_Click(sender As Object, e As EventArgs) Handles btnCreateAudition.Click


    Protected Sub btnCreateAudition_Click(sender As Object, e As EventArgs) Handles btnCreateAudition.Click

        Dim audition_ID As Integer = 0
        Dim audition_Status As Integer = 0
        Dim ins_ID As Integer = DropDownList1.SelectedValue
        Dim ins_name As String = GetIns_Name(DropDownList1.SelectedValue)
        Dim judge1 As Integer = DropDownList2.SelectedValue
        Dim judge2 As Integer = DropDownList3.SelectedValue
        Dim judge3 As Integer = DropDownList4.SelectedValue
        Dim judge4 As Integer = DropDownList5.SelectedValue
        Dim judge5 As Integer = DropDownList6.SelectedValue
        Dim judgename1 As String = DropDownList2.SelectedValue
        Dim judgename2 As String = DropDownList3.SelectedValue
        Dim judgename3 As String = DropDownList4.SelectedValue
        Dim judgename4 As String = DropDownList5.SelectedValue
        Dim judgename5 As String = DropDownList6.SelectedValue
        Dim auditionIDTest As Integer = 100001
        Using con As New SqlConnection("Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename=|DataDirectory|\BandDatabase.mdf;Integrated Security=True")
            Using cmd As New SqlCommand("Create_Audition")
                Using sda As New SqlClient.SqlDataAdapter()
                    cmd.CommandType = CommandType.StoredProcedure
                    cmd.Parameters.AddWithValue("@audition_date", Calendar1.SelectedDate)
                    cmd.Parameters.AddWithValue("@audition_location", txtauditionlocation.Text)
                    cmd.Parameters.AddWithValue("@audition_status", audition_Status)
                    cmd.Parameters.AddWithValue("@instrument_name", ins_name)
                    cmd.Parameters.AddWithValue("@ins_ID", ins_id)
                    cmd.Parameters.AddWithValue("@judge1", judge1)
                    cmd.Parameters.AddWithValue("@judge2", judge2)
                    cmd.Parameters.AddWithValue("@judge3", judge3)
                    cmd.Parameters.AddWithValue("@judge4", judge4)
                    cmd.Parameters.AddWithValue("@judge5", judge5)
                    cmd.Parameters.AddWithValue("@judgename1", judgename1)
                    cmd.Parameters.AddWithValue("@judgename2", judgename2)
                    cmd.Parameters.AddWithValue("@judgename3", judgename3)
                    cmd.Parameters.AddWithValue("@judgename4", judgename4)
                    cmd.Parameters.AddWithValue("@judgename5", judgename5)
                    cmd.Parameters.AddWithValue("@audition_IDTest", auditionIDTest)
                    cmd.Connection = con
                    con.Open()
                    'No error if below line is commented out, but DB isn't updated
                    audition_ID = Convert.ToInt32(cmd.ExecuteScalar())
                    con.Close()
                End Using
            End Using
        End Using
    End Sub

CREATE PROCEDURE [dbo].[Create_Audition]
       @audition_date DATE,
       @audition_status INT,
       @audition_location NVARCHAR,
       @ins_ID INT,
       @instrument_name INT,
       @judge1 INT,
       @judge2 INT,
       @judge3 INT,
       @judge4 INT,
       @judge5 INT,
       @judgename1 NVARCHAR,
       @judgename2 NVARCHAR,
       @judgename3 NVARCHAR,
       @judgename4 NVARCHAR,
       @judgename5 NVARCHAR,
       @audition_IDTest INT
AS
BEGIN

              INSERT INTO [Audition] 
                           ([audition_date]
                           ,[ins_ID]
                           ,[insturment_name]
                           ,[audition_location]
                           ,[audition_status])
              VALUES
                           (@audition_date
                           ,@ins_ID
                           ,@instrument_name
                           ,@audition_location
                           ,@audition_status)

              SELECT SCOPE_IDENTITY() -- Audition_ID


       END
BEGIN

              INSERT INTO [Judge_Audition] 
                           ([UserID]
                           ,[judge_username]
                           ,[audition_ID]
                           )


              VALUES
                           (@judge1,
                            @judgename1,
                            @audition_IDTest
                          )

              SELECT SCOPE_IDENTITY() -- J_ID
       END
BEGIN

              INSERT INTO [Judge_Audition] 
                           ([UserID]
                           ,[judge_username]
                           ,[audition_ID]
                          )
              VALUES
                           (@judge2,
                           @judgename2,
                           @audition_IDTest
                          )

              SELECT SCOPE_IDENTITY() -- J_ID
       END
BEGIN

              INSERT INTO [Judge_Audition] 
                           ([UserID]
                           ,[judge_username]
                           ,[audition_ID]
                          )
              VALUES
                           (@judge3,
                           @judgename3,
                           @audition_IDTest
                          )

              SELECT SCOPE_IDENTITY() -- J_ID
       END
BEGIN

              INSERT INTO [Judge_Audition] 
                           ([UserID]
                           ,[judge_username]
                           ,[audition_ID]
                          )
              VALUES
                           (@judge4,
                           @judgename4,
                           @audition_IDTest
                          )

              SELECT SCOPE_IDENTITY() -- J_ID
       END

BEGIN

              INSERT INTO [Judge_Audition] 
                           ([UserID]
                           ,[judge_username]
                           ,[audition_ID]
                          )
              VALUES
                           (@judge5,
                           @judgename5,
                            @audition_IDTest

                          )

              SELECT SCOPE_IDENTITY() -- J_ID
       END