oracle之常用语句

1.查询用户数据所占空间:select sum(bytes)/1024/1024 from user_extents;

2.按字段的首字母进行查询

select * from table order by NLSSORT(SUBSTR(col,1,1))

顺便普及下nlssort的用法

nlssort是在9i中才加入的特性 三句话说明nlssort的用法

 --按拼音查询
  SELECT * FROM table ORDER BY NLSSORT(col,'NLS_SORT = SCHINESE_PINYIN_M') 
  --按拼音笔划
 SELECT * FROM table ORDER BY NLSSORT(col,'NLS_SORT = SCHINESE_STROKE_M') 
--按拼音部首
 SELECT * FROM table ORDER BY NLSSORT(col,'NLS_SORT = SCHINESE_RADICAL_M')