請問大大們，這樣的寫法執行起來是不是會很慢? 是否有其他的寫法呢?
先謝謝各位大大了~~~
SELECT DPC_PONO AS M_NO,
MPC_Frm AS Frm,(SELECT Frm_SName FROM pot_Firm WHERE Frm_ID=MPC_Frm) AS Frm_SName,
MPC_Date AS C_Date,MPC_NO AS C_NO,
(SELECT C_Date FROM qcv_rptCData WHERE C_NO=DPC_CNO) AS M_Date,
DPC_SCT AS SCT,DPC_ECT AS ECT,DPC_Man AS C_Man,
(SELECT Emp_CName FROM hrt_Employee WHERE Emp_ID=DPC_Man) AS Emp_CName,
(SELECT C_Man FROM qcv_rptCData WHERE C_NO=DPC_CNO) AS M_Man,
(SELECT C_MName FROM qcv_rptCData WHERE C_NO=DPC_CNO) AS M_Name,
DPC_FLW AS FLW,(SELECT FC_Name FROM qct_FlowClass WHERE FC_ID=DPC_FLW) AS FC_Name,
DPC_SUR AS SUR,(SELECT FP_Name FROM qct_FaceProc WHERE FP_ID = DPC_SUR) AS FP_Name,
DPC_HPH AS HPH,DPC_CQty AS CQty,(DPC_YQty DPC_NQty) AS Qty,DPC_YQty AS YQty,
DPC_NQty AS NQty,EXP_Qty AS EQty,DPC_Mark AS Mark,DPC_EXP AS EXP,EXP_Sta,
(Case MPC_Cfm WHEN 0 Then '進行中' ELSE '已完成' END ) AS Cfm,
EXP_Duty AS Duty,(SELECT Dept_SName From hrt_Department WHERE Dept_ID = EXP_Duty) AS Dept_SName,
EXP_LEX AS LEX,(SELECT LEX_Name From qct_LastExc WHERE LEX_ID = EXP_LEX) AS LEX_Name,
DPC_PDID AS PDID,(SELECT Prd_CName FROM stt_Product WHERE Prd_ID=DPC_PDID) AS Prd_CName,
(CASE DPC_CKD WHEN 0 THEN '一次檢驗' WHEN 1 THEN '分批檢驗' WHEN 2 THEN '抽樣檢驗' Else '首件檢驗' END) AS CKD,
(SELECT C_PName FROM qcv_rptCData WHERE C_NO=DPC_CNO) AS C_PName
FROM qct_PCDetail D LEFT OUTER JOIN qct_PCMaster M ON DPC_NO = MPC_NO
LEFT OUTER Join qct_Exception E ON DPC_EXP = EXP_NO

快或慢涉及資料量的大小... 以及資料表之間規劃是否合理化，至於語法的問題是絲枝末節了。

沒有下WHERE條件式嗎？這樣好像是要把指定的資料表內的資料全取回來，資料量如果大一些，速度會慢是可想而知的了。

其實我的資料表才398筆，用我上面的語法跑的話 大概要五十八秒才出來的!!
今天閒到發慌就開始找尋原因。我發現....上面的語法有太多(Select .....) as 的
且有重復跟同表格做查詢資料 如:
(SELECT C_Date FROM qcv_rptCData WHERE C_NO=DPC_CNO) AS M_Date
(SELECT C_Man FROM qcv_rptCData WHERE C_NO=DPC_CNO) AS M_Man,
(SELECT C_MName FROM qcv_rptCData WHERE C_NO=DPC_CNO) AS M_Name,
(SELECT C_PName FROM qcv_rptCData WHERE C_NO=DPC_CNO) AS C_PName
這四句~~~小弟剛剛把他改了一下 用 join的方式~~~神奇的事發生了
要58秒的查詢時間竟變成短短2秒!!
其實會這樣寫，是記得有人跟我說過用SELECT 方法會比 Join還要快~~
真不知道啥情狀下該用那個來寫才對 @@!!
不過謝謝兩位大大的回覆囉~~

其實並不是JOIN速度快過SELECT >..<!!
資料庫對搜尋過的資料會建立INDEX 所以當你搜尋同樣的東西,速度當然會快很多~

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昏睡~
不昏睡~
不由昏睡~