>What's the correct syntax for converting this to SQL:
>
>

>IIf(IIf(CAST(RQ.RQ_JOB AS DECIMAL) < sf.PeriodOrderedQty, 0, CAST(RQ.RQ_JOB AS DECIMAL)- sf.PeriodOrderedQty) <> RQ.RQ_QTY_REQ,'Yes','') AS [Update PK Qty Required?], 
>

>
>Thanks


IIF translates to CASE statement, so

CASE when (case when CAST(RQ.RQ_JOB AS DECIMAL(19,4)) < sf.PeriodOrderedQty 
then 0 else CAST(RQ.RQ_JOB AS DECIMAL(19,4))- sf.PeriodOrderedQty end) = RQ.RQ_QTY_REQ 
then '' else 'Yes' end as  [Update PK Qty Required]

See also http://blogs.lessthandot.com/index.php/DataMgmt/DBProgramming/always-include-precision-and-scale-with about why did I do another change (specified scale and precision for the decimal).