select 1

from PMADW.GET_WX_DATAPUSH_NEW_CHECK A

INNER JOIN PMADW.V_EXCEPTION_QTY_MAIN B on DECODE( A.VALUE_NAME,B.V_QTY_CODE,1,B.PARENTID,1,0) = 1

    and A.DAY_ID = B.DAY_ID

    AND  B.N_GRANULARITY = 1

where A.DAY_ID = TO_DATE('{$yest}','yyyy-mm-dd')

    and A.IS_NEW = 0

    AND  EXISTS( SELECT value_name FROM PMADW.GET_WX_DATAPUSH_NEW_CHECK  t2

         WHERE  t2.DAY_ID = b.DAY_ID

         AND t2.value_name = nvl(b.parentid,b.V_QTY_CODE))

    AND  ROWNUM <=1

DECODE(a,b,1,c,2,0)

解释：

    switch(a){

        case b:

            return 1;

            break;

        case c:

            return 2;

            break;

        default:

            return 0;

    }

nvl(a,b)

解释：

    return (a != '') ? a : b;