写法1:
select * from tablename where date_time = ( select max(date_time) from tablename where date_time < to_date('%s','YYYY-MM-DD HH24:MI:SS'))写法2:
SELECT * FROM (SELECT * FROM ( SELECT * FROM tablename order by DATE_TIME DESC) WHERE ROWNUM=1)写法1是不是比写法2性能要好?能不能给我理由,谢谢!
select * from tablename where date_time = ( select max(date_time) from tablename where date_time < to_date('%s','YYYY-MM-DD HH24:MI:SS'))写法2:
SELECT * FROM (SELECT * FROM ( SELECT * FROM tablename order by DATE_TIME DESC) WHERE ROWNUM=1)写法1是不是比写法2性能要好?能不能给我理由,谢谢!
解决方案 »
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