sql - Update on a left join? - Stack Overflow

Try using COALESCE()? UPDATE tab2 SET Change = COALESCE(tab2.Value ,0) - COALESCE(tab1.Value ,0) FROM Table_Name tab1 LEFT OUTER JOIN Table_Name tab2 ON tab2.COBDate = '2012-5-18' AND tab1.FileName = tab2.FileName AND tab1.ID = tab2 ...

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