oracle常用语句

查询及删除重复记录的SQL语句

1、查找表中多余的重复记录，重复记录是根据单个字段（Id）来判断

select * from 表 where Id in (select Id from 表 group byId having count(Id) > 1)

2、删除表中多余的重复记录，重复记录是根据单个字段（Id）来判断，只留有rowid最小的记录

DELETE from 表 WHERE (id) IN ( SELECT id FROM 表 GROUP BY id HAVING COUNT(id) > 1) AND ROWID NOT IN (SELECT MIN(ROWID) FROM 表 GROUP BY id HAVING COUNT(*) > 1);

3、查找表中多余的重复记录（多个字段）

select * from 表 a where (a.Id,a.seq) in(select Id,seq from 表 group by Id,seq having count(*) > 1)

4、删除表中多余的重复记录（多个字段），只留有rowid最小的记录

delete from 表 a where (a.Id,a.seq) in (select Id,seq from 表 group by Id,seq having count() > 1) and rowid not in (select min(rowid) from 表 group by Id,seq having count()>1)

5、查找表中多余的重复记录（多个字段），不包含rowid最小的记录

select * from 表 a where (a.Id,a.seq) in (select Id,seq from 表 group by Id,seq having count() > 1) and rowid not in (select min(rowid) from 表 group by Id,seq having count()>1)

6.随机从0到100选择一个数字

select trunc(dbms_random.value(0,100)) from dual;

查询用户下所有表数据：

select t.table_name,t.num_rows from user_tables t

若以上SQL查找不到，执行如下脚本即可：

create or replace function count_rows(table_name in varchar2,
                              owner in varchar2 default null)
return number
authid current_user
IS
   num_rows number;
   stmt varchar2(2000);
begin
   if owner is null then
      stmt := 'select count(*) from "'||table_name||'"';
   else
      stmt := 'select count(*) from "'||owner||'"."'||table_name||'"';
   end if;
   execute immediate stmt into num_rows;
   return num_rows;
end;

之后，再查

select table_name, count_rows(table_name) nrows from user_tables ，

查询用户下所有表表名：

select * from dba_tables where owner=’用户名大写’;

alter tablespace  USERS rename to HYRSRCDATA—–修改表空间名字