c# - 抛出类型为 'System.Data.StrongTypingException' C# 的异常

Question

if ((booking.BookingsVoucher[i].RedemptionReloc != null)). 

我在这里遇到异常。 RedemptionReloc 在数据库中有空值

Redemption TimeSttmp 
NULL 
Redemption Reloc 
NULL 
RedeemedCurrencyC 
NULL 
Redeemed Amo_ 
NULL 

尝试使用 DBNULL.value.equal(booking.BookingsVoucher[i].RedemptionReloc)。但这也会引发异常。这是异常日志

Exception in adding Voucher Details: System.Data.StrongTypingException: The value for column 'RedemptionReloc' in table 'BookingsVoucher' is DBNull. ---> System.InvalidCastException: Unable to cast object of type 'System.DBNull' to type 'System.String'.

Answer 1

将 NullValue 项目更改为 Null 或 Empty 并进行相应检查。

DataSet1 ds1 = new DataSet1();

        SqlConnection cn = new SqlConnection(System.Configuration.ConfigurationManager.ConnectionStrings["ContosoUniversity2ConnectionString"].ConnectionString);

        using (cn)
        {
            using (SqlDataAdapter adapter = new SqlDataAdapter("SELECT * FROM Department", cn))
            {
                adapter.Fill(ds1.Department);
                foreach (DataSet1.DepartmentRow row in ds1.Department.Rows)
                {
                    if (row.Name != null)
                    {
                        Console.WriteLine(row.Name);
                    }

                }
            }
        }