Checking for DBNull
- by Jim Lahman
Using a table adapter to a SQL Server database table that returns a NULL record. We determine the fields are NULL by comparing against System.DBNull Looking the NULL records in SQL Management studio Using a table adapter to retrieve a record 1: try
2: {
3: this.vTrackingTableAdapter.FillByTrkZone(this.dsL1Write.vTracking, iTrkZone);
4: }
5: catch (Exception ex)
6: {
7: sLogMessage = String
8: .Format("Error getting coil number from tracking table at {0} - {1}",
9: sTrkName,
10: ex.Message);
11: throw new CannotReadTrackingTableException(sLogMessage);
12: }
Looking at the record as it returned from the table adapter:
ItemArrayObject
Column
[0]
ChargeCoilNumber
[1]
HeadWeldZone
[2]
TailWeldZone
[3]
ZoneLen
[4]
ZoneCoilLen
[5]
Confirmed
[6]
Validated
[7]
EntryWidth
[8]
EntryThickness
Since each item in the ItemArray is an object, we can test for null
1: if (dsL1Write.vTracking.Rows[0].ItemArray[0] == System.DBNull.Value)
2: {
3: throw new NoCoilAtPORException("NULL coil found at tracking zone " + sTrkName);
4: }
If no records were returned by the table adapter
1: if (dsL1Write.vTracking.Rows.Count == 0)
2: {
3: throw new NoCoilAtPORException("No coils found at tracking zone " + sTrkName);
4: }
