How to Convert a Nullable DateTime variable's null value to DbNull.Value

问题

I have a nullable DateTime Variable. And I want to write it to SQL DB. When i try to insert:

If the variable has value there is no problem.

But if it hasn't a value, insertion interrupting with an error.

I want to ask: How can we insert nullable DateTime to Sql via DbCommand Parameter?

(P.S. : Sql column is nullable too.)

DateTime? myDate = null;
DbCommand dbCommand = new DbCommand();
dbCommand.Parameters.Add("NullableSqlDateField", DbType.DateTime, myDate);

回答1:

Try the null coalescing operator:

dbCommand.Parameters.Add("NullableSqlDateField", DbType.DateTime, (object) myDate ?? DbNull.Value);

回答2:

try this

if(myDate.HasValue)
  dbCommand.Parameters.Add("NullableSqlDateField", DbType.DateTime, myDate.Value);
else
  dbCommand.Parameters.Add("NullableSqlDateField", DbType.DateTime, DbNull.Value);

来源：https://stackoverflow.com/questions/8669107/how-to-convert-a-nullable-datetime-variables-null-value-to-dbnull-value