SqlDataReader中的可空DateTime值

Question

How do we read integer null values from SqlDataReader ?

CREATE TABLE [dbo].[Mem_Basic] (
  [Id]          INT           IDENTITY (1, 1) NOT NULL,
  [Mem_Email]   VARCHAR (50)  NULL,
  [Mem_DOB]     DATE          NULL,
  [Mem_ResPin]  INT           NULL,
  PRIMARY KEY CLUSTERED ([Id] ASC)
);

For string and integer I use

if (reader.Read() == true)
{
  mb.Mem_Email = reader["Mem_Email"] == System.DBNull.Value ? null : (string)reader["Mem_Email"];
  mb.Mem_ResPin = reader["Mem_ResPin"] as int? ?? default(int);
 }

But how do I read the date in same manner from reader?

//mb.Mem_DOB = (Convert.ToDateTime(reader["Mem_DOB"]));

Answer 1

mb.Mem_DOB = reader["Mem_DOB"] == DBNull.Value
                 ? (DateTime?) null
                 : (DateTime) reader["Mem_DOB"];

The mb.Mem_DOB should be declared as a DateTime?

Don't use Convert.ToDateTime . The value is already a DateTime , so just cast it.

Answer 2

DateTime? Mem_DOB = null;

mb.Mem_DOB = reader["Mem_DOB"] == System.DBNull.Value ? null : Convert.ToDateTime(reader["Mem_DOB"]);

Answer 3

mb.Mem_DOB = reader["Mem_DOB"] == System.DBNull.Value ? DateTime.MinValue : Convert.ToDateTime(reader["Mem_DOB"]);

Answer 4

You can check if it is null or not.

int i = reader.GetOrdinal("Mem_DOB")
if( reader.IsDBNull(i))
   mb.Mem_DOB = someDefaultValueforyourdatetime; //assign null of Mem_DOB is nullable
else
   mb.Mem_DOB = Convert.ToDateTime(reader(i));

Though instead of using Convert.ToDateTime directly, i would recommend using DateTime.TryParse or DateTime.TryParseExact .