c# - Scalar Variable @AssetNumber

Question

When i step through the code the parameter is being added, its just when the sql command is executed, it throws this error up

  public static DataTable GetPostings2(string AssetNumberV, string PeriodFromV, string PeriodToV)
    {
        DataTable dtGetPostings2;
        try
        {
            dtGetPostings2 = new DataTable("GetPostings");

            SqlParameter AssetNumber = new SqlParameter("@AssetNumber", SqlDbType.VarChar, 6);
            AssetNumber.Value = AssetNumberV;

            SqlParameter PeriodFrom = new SqlParameter("@PeriodFrom", SqlDbType.VarChar, 6);
            PeriodFrom.Value = PeriodFromV; 

            SqlParameter PeriodTo = new SqlParameter("@PeriodTo", SqlDbType.VarChar, 6);
            PeriodTo.Value = PeriodToV; 

            SqlCommand scGetPostings2 = new SqlCommand("SELECT * FROM [POSTING] WHERE [ASSET_NO] = @AssetNumber And PERIOD >= @PeriodFrom AND PERIOD <= @PeriodTo ORDER by PERIOD, JOUR_REF, JOUR_LINE", DataAccess.AssetConnection);

            SqlDataAdapter sdaGetPostings2 = new SqlDataAdapter();
            sdaGetPostings2.SelectCommand = scGetPostings2;
            sdaGetPostings2.Fill(dtGetPostings2);

            return dtGetPostings2;

        }
        catch (Exception ex)
        {
            MessageBox.Show("Error Retriving Posting Details: Processed with this error:" + ex.Message);
            return null;
        }
    }

Answer 1

列出的代码不会将参数添加到SqlCommand.Parameters 集合中。例如：

SqlCommand scGetPostings2 = new SqlCommand("SELECT * FROM [POSTING] WHERE [ASSET_NO] = @AssetNumber And PERIOD >= @PeriodFrom AND PERIOD <= @PeriodTo ORDER by PERIOD, JOUR_REF, JOUR_LINE", DataAccess.AssetConnection);
scGetPostings2.Parameters.Add(AssetNumber);
scGetPostings2.Parameters.Add(PeriodFrom );
scGetPostings2.Parameters.Add(PeriodTo );

// Code continues as above
SqlDataAdapter sdaGetPostings2 = new SqlDataAdapter();
// And so on