Delete from 3 tables

Question

I have 3 tables I need to delete partial data from.
ObservedSpeciesCollectionMethodID CollectionMethodID ObservedSpeciesID
109150                            29                
222898
109149                            29                
222897
109148                            19                
222900
109147                            19                
222899
ObservedSpeciesMeasurementID ObservedSpeciesID NumericValueHigh
79608                        222898            2
79607                        222897            1
79606                        222900            4
79605                        222899            3
ObservedSpeciesID ObservationSiteID SpeciesID
222898            146620            1108
222897            146620            1053
222900            146620            1108
222899            146620            1053
Table names are:
  ObservedSpeciesCollectionMethod
  ObservedSpeciesMeasurement
  ObservedSpecies
The only information I have is CollectionMethodID and ObservationSiteID.
So if CollectionMethodID = 19:
Delete rows 3 and 4 from all 3 tables.
Any help is greatly appreciated

Answer 1

Try
declare @CollectionMethodToDelete int= 19;declare @ObservationSiteID int =  146620;   
if object_ID('TempDB..#DeleteSpecies', N'U') IS NOT NULL DROP TABLE #DeleteSpecies
select ObservedSpeciesID
into #DeleteSpecies
from ObservedSpeciesCollectionMethod CM
where CollectionMethodID = @CollectionMethodToDelete and not exists (select 1
from ObservedSpeciesCollectionMethod CM1 where CM1.ObservedSpeciesID = CM.ObservedSpeciesIDAND CM.CollectionMethodID <> CM1.CollectionMethodID) -- we're OK to delete the species that were only observed by that method
try
begin transaction
delete from ObservedSpeciesMeasurement where ObservedSpeciesID IN (select ObservedSpeciesID from #DeleteSpecies)
delete from ObservedSpeciesCollectionMethod where CollectionMethodID = @CollectionMethodToDelete
delete from ObservedSpecies where ObservedSpeciesID IN (select ObservedSpeciesID from #DeleteSpecies)AND ObservationSiteID = @ObservationSiteID;
commit transaction
end try
begin catch
DECLARE @ErrorSeverity INT
,@ErrorNumber INT
,@ErrorState INT
,@ErrorLine INT
,@ErrorProc NVARCHAR(200);
-- Grab error information from SQL functions
SET @ErrorSeverity = ERROR_SEVERITY();
SET @ErrorNumber = ERROR_NUMBER();
SET @ErrorMessage = ERROR_MESSAGE();
SET @ErrorState = ERROR_STATE();
SET @ErrorLine = ERROR_LINE();
SET @ErrorProc = ERROR_PROCEDURE();
SET @ErrorMessage = 'Problem deleting species. SQL Server Error Message is: ' + CAST(@ErrorNumber AS VARCHAR(10)) + ' in procedure: ' + @ErrorProc + ' Line: ' + CAST(@ErrorLine AS VARCHAR(10)) + ' Error text: ' + @ErrorMessage;
-- Not all errors generate an error state, to set to 1 if it's zero
IF @ErrorState = 0
SET @ErrorState = 1;
-- If the error renders the transaction as uncommittable or we have open transactions, we may want to rollback
IF @@TRANCOUNT > 0
BEGIN
ROLLBACK TRANSACTION
END
RAISERROR (
@ErrorMessage
,@ErrorSeverity
,@ErrorState
,@ErrorNumber
END CATCH
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