Question

In SSIS 2008 I have a Script Task that checks if a table exists in a database and sets a boolean variable.

In my Data Flow I do a Conditional Split based on that variable, so that I can do the appropriate OLE DB Commands based on whether that table exists or not.

If the table does exist, the package will run correctly. But if the table doesn’t exist, SSIS is checking metadata on the OLE DB Command that isn’t being run, determine the table isn’t there, and failing with an error before doing anything.

There doesn’t seem to be any way to catch or ignore that error (e.g. I tried increasing MaximumErrorCount and various different ErrorRowDescription settings), or to stop it ever validating the command (ValidateExternalMetadata only seems to affect the designer, by design).

I don’t have access to create stored procedures to wrap this kind of test, and OLE DB Commands do not let you use IF OBJECT_ID('') IS NOT NULL prefixes on any statements you’re doing (in this case, a DELETE FROM TableName WHERE X = ?).

Is there any other way around this, short of using a script component to fire off the DELETE command row-by-row manually?

Answer 1

You can use Script component to execute DELETE statement for each row in input path but that might be very slow depending on number of rows to be deleted.

You can:

1. Store PKs of records that should be deleted to a database table (for instance: TBL_TO_DEL)
2. Add Execute SQL Task with SQL query to delete records by joining TBL_TO_DEL with table that You want to delete records from
3. Put precedence constraint on path between your data flow and Execute SQL task (constraint based on your variable)

This solution is much faster than deleting row by row.

If for some reason You can’t create new table, check my answer on SSIS Pass Datasource Between Control Flow Tasks to see other ways to pass data to next data flow where You can use OleDb source and OleDb command. Whichever way You choose, key is in constraint that will or will not execute following task (Execute SQL task or data flow) depending on value in variable.

Note that Execute SQL task will not validate query and as such will fail at runtime if constraint is satisfied and table doesn’t exist. If You use another Data Flow instead of Execute SQL Task, set DelayedValidation property to true. It means that task will be validated at the moment prior to executing particular task, not anytime earlier.