排序:将一列1-10正序,11-20倒序,20-?正序,
前两步已经解决,请高人指点。SELECT * FROM (SELECT * FROM TB ORDER BY NO1)WHERE ROENUM < 10
UNION ALL
SELECT * FROM (SELECT * FROM (SELECT NO1 FROM TB ORDER BY NO1 ) WHERE ROWNUM <20 ORDER BY NO1 DESC) WHERE ROWNUM <10;我接触数据库不久,上面的句子我想能够优化。
请帮忙解决从21条以后未知条数的降序排列。谢谢。
前两步已经解决,请高人指点。SELECT * FROM (SELECT * FROM TB ORDER BY NO1)WHERE ROENUM < 10
UNION ALL
SELECT * FROM (SELECT * FROM (SELECT NO1 FROM TB ORDER BY NO1 ) WHERE ROWNUM <20 ORDER BY NO1 DESC) WHERE ROWNUM <10;我接触数据库不久,上面的句子我想能够优化。
请帮忙解决从21条以后未知条数的降序排列。谢谢。
SELECT * FROM (SELECT * FROM TB ORDER BY NO1)WHERE ROWNUM < 1010-20
SELECT * FROM (SELECT * FROM TB ORDER BY NO1)WHERE ROWNUM < 20
MINUS
SELECT * FROM (SELECT * FROM TB ORDER BY NO1)WHERE ROWNUM < 1020-?
SELECT * FROM TB ORDER BY NO1
MINUS
SELECT * FROM (SELECT * FROM TB ORDER BY NO1)WHERE ROWNUM < 20
20-? 正序
SELECT * FROM(SELECT * FROM TB ORDER BY NO1)
MINUS
SELECT * FROM (SELECT * FROM TB ORDER BY NO1)WHERE ROWNUM < 20
倒序SELECT * FROM(
SELECT * FROM(SELECT * FROM TB ORDER BY NO1)
MINUS
SELECT * FROM (SELECT * FROM TB ORDER BY NO1)WHERE ROWNUM < 20)
ORDER BY NO1 DESC