學習紀錄

最近在做統計報表，大家都是這樣做的。稍微練習一下 ..

可以把WITH當成一種子查詢，其實我解讀她更像是TempTABLE 可以反覆的讀取內容的資料

並且提高SQL的可讀性

with MC(促銷名稱) as
(
select MB004 NA from POSMC
LEFT JOIN POSMB ON MB001=MC001 AND MB002 = MC002 AND MB003 = MC003
where MC004 = '4000005'
UNION ALL

select MI004 NA from POSMJ
LEFT JOIN POSMI ON MI001=MJ001 AND MI002 = MJ002 AND MI003 = MJ003
where MJ004 = '5000001'
UNION ALL

select MO004 NA from POSMP
LEFT JOIN POSMO ON MO001=MP001 AND MO002 = MP002 AND MO003 = MP003
where MP005 = '5000001'
)

select * from MC

這樣看起來SQL的閱讀性更佳了 ^Q^