Variables in Update activity

Hi guys,

I wanted to know if it's possible to use variables(instance or otherwise) in the Update step. I'm getting errors when MSSQL tries to generate the prepared statement. I'm fairly certain this should be possible, so I'm not sure why I'm getting errors.

07/05/2017 10:32:41 AM ODBC error: [Microsoft][SQL Server Native Client 10.0][SQL Server]Incorrect syntax near ')'. SQLState: 37000

07/05/2017 10:32:41 AM ODBC error: [Microsoft][SQL Server Native Client 10.0][SQL Server]Statement(s) could not be prepared. SQLState: 37000

07/05/2017 10:32:41 AM SQL statement 'INSERT INTO wkf188035_86_1 (iRecTrnState, iPKey1, sPKey1_1, sPKey1_2, iPKey1_3, sPKey_1, sPKey_2, iPKey_3, sFld1065550762, sFld1066795947, iFld1067254700, iSrc1) SELECT   0, case when W0.iIClientId <> 0 then W0.iIClientId else NULL end, C1

07/05/2017 10:32:41 AM .sName, C1.sCampaignName, C1.iClientId, NULL, NULL, NULL, substring(cast(NULL as varchar(255)), 1, 255), substring(cast(NULL as varchar(255)), 1, 255), W0.iIClientId, W0.iIClientId FROM wkf188035_85_1 W0 LEFT JOIN [AAAAA].[dbo].XXXXX

07/05/2017 10:32:41 AM C1 JOIN [BBBB].[dbo].[YYYYYY] C2 ON (C2.iClientId = W0.iIClientId)' could not be executed.

P.s. I've removed the database and table names from the log for propriety's sake.

Thanks in advance!

--Erik