LINQ - LINQ Optional Parameter not passing NULL correctly?
Asked By Nick S
02-Aug-10 09:45 AM
Hi,
I'm using LINQ in my application, and I have an optional int data type in my WCF web service.
So:
public List<Test> GetRecords(int seq1, int? seq2)
{
TestDataContext db = new TestDataContext ();
var myList = (from test in db.test
where test.SEQ_GROUP == seq1 && test.SEQ_STAFF == seq2
select new Test
{
Item = System.Convert.ToString(test.SEQUENCE),
ID = test.ID,
Description = test.DESCRIPTION,
Name = test.Name,
Desc = test.Desc
}
);
Now, if I execute this, the SQL basically queries the database and says SEQ_STAFF = 1
Howvever, if I don't populate seq2 as the optional integer... the SQL code executes as SEQ_STAFF = null
This should be executing SEQ_STAFF IS NULL
Can anyone help here?
THanks,
Nick
Indranil Chatterjee replied to Nick S
That is a common limitation of LINQ to SQL.
Try this instead:
from test in db.test
where test.SEQ_GROUP == seq1 && ((seq2 == null && test.SEQ_STAFF == null) || test.SEQ_STAFF == seq2)
select new Test
//The point is, when the comparison is explicitly done against null, LINQ to SQL generates a proper IS NULL clause
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