CODEWITHSUNDEEP
c#sqldatetimenull
user971352
user971352

Reputation: 3

Null data on DateTime from database

I've been through the various answers here with this one already, but none give an answer that actually works. The core issue (obviously) is that DateTime hasn't any concept of NULL, so the usual 

string dateValue = myReader.IsDBNull (4) ? null : myReader.GetDateTime(4) ;

doesn't work.

I've tried 

DateTime? nextDue = myReader.GetDateTime(3) == DBNull.Value ? null : (DateTime?)myReader.GetDateTime (3) ;

but that gives

Operator '==' cannot be applied to operands of type 'System.DateTime' and 'System.DBNull'

Changing to

DateTime? nextDue = myReader.GetDateTime(3) = DBNull.Value ? null : (DateTime?)myReader.GetDateTime (3) ;

produces

Cannot implicitly convert type 'System.DBNull' to 'bool'

I ended up changing the SQL to not output NULL values, but I'd still like to crack this one, as it will be useful elsewhere

Upvotes: 0

Views: 296

Answers (5)

Cris
Cris

Reputation: 13351

try

  DateTime? nextDue = myReader.GetValue(3) == DBNull.Value ? null : (DateTime?)myReader.GetDateTime (3);

Upvotes: 0

Quinton Bernhardt
Quinton Bernhardt

Reputation: 4803

Firstly Your syntax here:

DateTime? nextDue = myReader.GetDateTime(3) = DBNull.Value ? null : (DateTime?)myReader.GetDateTime (3) ;

id wrong. Should be:

DateTime? nextDue = myReader.GetDateTime(3) == DBNull.Value ? null : (DateTime?)myReader.GetDateTime (3) ;

Secondly you could use:

DateTime? nextDue = myReader.IsDBNull(3) ? null : (DateTime?)myReader.GetDateTime (3) ;

Upvotes: 1

Ann L.
Ann L.

Reputation: 13975

You could try

DateTime? nextDue = myReader.IsDbNull(3) ? null : (DateTime?) myReader.GetDateTime (3)

Upvotes: 1

flup
flup

Reputation: 27103

You need to cast the null to DateTime?:

DateTime? nextDue = myReader.IsDBNull(3) ? 
    null as DateTime? : 
    (DateTime?)myReader.GetDateTime (3)

Upvotes: 0

Daniel Kelley
Daniel Kelley

Reputation: 7747

Just use:

DateTime? nextDue;
if (myReader.GetDateTime(3) == DBNull.Value)
    nextDue = myReader.GetDateTime(3);
else
    nextDue = null;

Alternatively:

DateTime? nextDue;
if (myReader.IsDBNull(3))
    nextDue = myReader.GetDateTime(3);
else
    nextDue = null;

Upvotes: 0

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