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oracle 使用leading, use_nl, rownum调优
阅读量:793 次
发布时间:2023-02-24

本文共 1365 字,大约阅读时间需要 4 分钟。

Oracle??????????COUNT??????

?Oracle?????????COUNT?????????????????????????COUNT?????????????

COUNT????????????????????????????????????????????????COUNT??????????????????????????????

???COUNT???????????

1. ???????

???????COUNT????????????????????????????????????????????????????

2. COUNT???????

COUNT??????????????????????????????????????????????????????

3. COUNT?????????

???COUNT?????????????????

3.1 ?????rownum???

?????????????????????????????????????

SELECT COUNT(*) FROM equipment e, sal_controledpnsnrange sc

WHERE sc.new_min_item_no <= e.itemnum
AND sc.new_max_item_no >= e.itemnum
AND sc.new_min_serial_no <= e.serialnum
AND sc.new_max_serial_no >= e.serialnum
AND e.itemnum = a_item_no
ORDER BY rownum

3.2 ??LEADING?USE_NL??

LEADING?USE_NL????????COUNT????????????????LEADING(e)?USE_NL(sc)???????????????

SELECT COUNT(sc.pmnum) FROM equipment e, sal_controledpnsnrange sc

WHERE sc.new_min_item_no <= e.itemnum
AND sc.new_max_item_no >= e.itemnum
AND sc.new_min_serial_no <= e.serialnum
AND sc.new_max_serial_no >= e.serialnum
AND e.itemnum = a_item_no
ORDER BY rownum

3.3 ??????

???????????????????????????????????????????????????

4. ?????????

???COUNT???????????????????

4.1 ?????

4.2 ???????

4.3 ????????

5. ?????

????????????????????????????????????????????????

?????????????COUNT??????????Oracle???????????

????????Oracle???????????????????????????????

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