原SQL如下：SQL的主要問題是紅色部分居然通過標量查詢，反復的查找與SQL相同的基表，很顯然這個可以用case when來簡化。

select
a.TRAN_ID,
a.AMOUNT,
a.BALANCE,
a.INVAMT,
a.PROMISED,
a.INVNO,
a.RCLNUM,
b.PROBLEM_ID, a.TRANTYPE,
a.TYPE,
a.DUEDATE,
a.INVDATE,
a.RCLDATE,
a.LASTTYPE,
a.LOCBAL,
a.CUSTNO,
b.STATUS,
a.PAYMENTS_PENDING,
isnull(( SELECT 'Y' FROM GPCOMP1.GPRECL aa with (NOLOCK) LEFT OUTER JOIN GPCOMP1.GPPROB b with (NOLOCK)ON (aa.tran_id = b.open_invoice_tran_id), GPCOMP1.GPTRCTRL c with (NOLOCK) WHERE aa.tran_id = a.tran_id AND aa.trantype = c.trantype AND ( ( c.CAPPLSTRAT = 'Y' AND (b.PROBLEM_ID IS NULL OR (b.PROBLEM_ID IS NOT NULL AND b.STATUS = 'C' )) AND ((c.DAPPLSTRAT = 'Y' AND c.CAPPLSTRAT = 'Y') OR C.SAPPLYSTRAT='Y' OR (C.SAPPLYSTRAT='N' AND aa.INVNO not in (select distinct (invno) from GPCOMP1.GPRECL r with (NOLOCK) where tran_id = (select open_invoice_tran_id from GPCOMP1.GPPROB p with (NOLOCK) where p.open_invoice_tran_id = r.tran_id)))) ) OR ( c.DAPPLSTRAT = 'Y' AND (b.PROBLEM_ID IS NOT NULL AND b.STATUS <> 'C' ) ) ) AND ( ( c.PPAPPLSTRAT = 'Y' AND aa.PAYMENTS_PENDING = 'Y' ) OR ( c.NPPAPPLSTRAT = 'Y' AND aa.PAYMENTS_PENDING != 'Y' ) ) ),'N')
as STRATEGIC

from GPCOMP1.GPRECL a with (NOLOCK) LEFT OUTER JOIN GPCOMP1.GPPROB b with (NOLOCK) on (b.OPEN_INVOICE_TRAN_ID = a.TRAN_ID)where a.CUSTNO= @P0 order by a.INVNO

?

changed to

select a.TRAN_ID, a.AMOUNT, a.BALANCE, a.INVAMT, a.PROMISED, a.INVNO, a.RCLNUM, b.PROBLEM_ID, a.TRANTYPE, a.TYPE, a.DUEDATE, a.INVDATE, a.RCLDATE, a.LASTTYPE, a.LOCBAL, a.CUSTNO, b.STATUS, a.PAYMENTS_PENDING, CASE WHEN c.PPAPPLSTRAT = 'Y'AND a.PAYMENTS_PENDING = 'Y'AND c.DAPPLSTRAT = 'Y'AND (b.PROBLEM_ID IS NOT NULL AND b.STATUS <> 'C' ) THEN 'Y' WHEN c.PPAPPLSTRAT = 'Y'AND a.PAYMENTS_PENDING = 'Y'AND c.CAPPLSTRAT = 'Y'AND (b.PROBLEM_ID IS NULL OR (b.PROBLEM_ID IS NOT NULL AND b.STATUS = 'C' ))AND (c.DAPPLSTRAT = 'Y' or C.SAPPLYSTRAT='Y' or (C.SAPPLYSTRAT='N' AND b.open_invoice_tran_id is null)) THEN 'Y' WHEN c.NPPAPPLSTRAT = 'Y'AND a.PAYMENTS_PENDING != 'Y'AND c.DAPPLSTRAT = 'Y'AND (b.PROBLEM_ID IS NOT NULL AND b.STATUS <> 'C' ) THEN 'Y' WHEN c.NPPAPPLSTRAT = 'Y'AND a.PAYMENTS_PENDING != 'Y'AND c.CAPPLSTRAT = 'Y'AND (b.PROBLEM_ID IS NULL OR (b.PROBLEM_ID IS NOT NULL AND b.STATUS = 'C' ))AND (c.DAPPLSTRAT = 'Y' or C.SAPPLYSTRAT='Y' or (C.SAPPLYSTRAT='N' and b.open_invoice_tran_id is null)) THEN 'Y' ELSE 'N' END as STRATEGIC FROM GPCOMP1.GPRECL a LEFT OUTER JOIN GPCOMP1.GPPROB b on (b.OPEN_INVOICE_TRAN_ID = a.TRAN_ID) LEFT OUTER JOIN GPCOMP1.GPTRCTRL c on (c.trantype = a.trantype) where a.CUSTNO= '12345' order by a.INVNO

轉載于:https://www.cnblogs.com/princessd8251/p/3847835.html

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