How do I handle null DateTime values included in a SQL SELECT * query?

Asked Oct 18 '21 at 00:19

Active Oct 18 '21 at 00:19

Viewed 192 times

After a SQL Select * query which results in one row, I set

        foundrows = Variables.PeopleTable.Select(SelectString);
        ThisRow = foundrows[0];

I set one DateTimePicker to a field StartDate:

        dateTimePicker1.Value = Convert.ToDateTime(ThisRow["StartDate"].ToString());

But a watch I have set on ThisRow["EndDate"] tells me that the name EndDate does not exist in the current context. The SQL table shows it is NULL. There are a lot of items on SO about how to handle this when the query result gives one value, rather than a complete row. Cast Null DateTime Value From Database? suggests it is simple, but if the value is not in this context that will stop any solution. I've checked the spelling of the field. Any suggestions?

asked Oct 18 '21 at 00:19

Ormond Stock

It'll be `if (ThisRow["EndDate"] != DBNull) {` – Jeremy Thompson Oct 18 '21 at 00:22
1

@Jeremy Thompson `DBNull.Value` ;) – Trevor Oct 18 '21 at 00:40
That gives 'DBNull' is a type, which is not valid in the given context. – Ormond Stock Oct 18 '21 at 01:13
The line "if (ThisRow["EndDate"] != DBNull.Value" threw an exception of type 'System.NullReferenceException' – Ormond Stock Oct 18 '21 at 01:33
@OrmondStock can you follow this exact example and step through your code. If you don't know how to debug watch a 5 min YouTube video https://stackoverflow.com/a/12508016/495455 - you're getting that NullReferenceException because `ThisRow` must be null why only debugging can tell you. – Jeremy Thompson Oct 18 '21 at 02:43
Thank you. Saved project, exited, rebooted, opened project, it works. Thanks for your help. – Ormond Stock Oct 18 '21 at 03:20
Also you should use `(DateTime)` cast rather than `Convert` with `ToString` which is really inefficient – Charlieface Oct 18 '21 at 11:25

How do I handle null DateTime values included in a SQL SELECT * query?

0 Answers0