rstext1 = "SELECT MIN(B.DTTM) FROM A, B" & _
" Where A.ordseq = B.ordseq " AND EXISTS(SELECT 1 FROM ORD C" & _
" Where B.ordseq = C.ordseq " & _
" AND C.ORDTY='C' AND C.ORDNO='" & Mo & "' )"
rstext = "SELECT MIN(B.DTTM) FROM ORDITMJOB A,STAFFTKT B,ORD C" & _
" Where A.ordseq = B.ordseq
" AND B.ORDSEQ=C.ORDSEQ " & _
" AND C.ORDTY='C'" & _
" AND C.ORDNO='" & Mo & "'"
哪個語句快,
為什麼???
" Where A.ordseq = B.ordseq " AND EXISTS(SELECT 1 FROM ORD C" & _
" Where B.ordseq = C.ordseq " & _
" AND C.ORDTY='C' AND C.ORDNO='" & Mo & "' )"
rstext = "SELECT MIN(B.DTTM) FROM ORDITMJOB A,STAFFTKT B,ORD C" & _
" Where A.ordseq = B.ordseq
" AND B.ORDSEQ=C.ORDSEQ " & _
" AND C.ORDTY='C'" & _
" AND C.ORDNO='" & Mo & "'"
哪個語句快,
為什麼???
有时候许多因素导致理论上快的语法在实际应用中也不一定最好
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程序,犹如人生。
怎麼試?
怎麼試?
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查询分析器有返回查询所用的时间啊,数据量够大的话,精确到秒也行了吧?