取整 & row_number & for & 动态DDL & 取随机值dbms_random.value

declare

begin

execute immediate "DDL"

end ;

drop table table1 purge;

查询数据库中的任意一条语句sql、 random .

mysql：

select * from table order by rand() limit 1

PostgreSQL:

select * from table order by random() limit 1

Microsoft SQL Server:

select top 1 colimn from table order by newid()

IBM DB2:

select column,rand() as cd from table order by cd fetch first 1 rows only

Oracle:

select column from (select column from table order by dbms_random.value) where rownum=1

e.g:

update table1

set id=( select id from (

select id from table1

order by dbms_random.value )

where rownum = 1 )

ORACLE:

row_number() over(partition by colum order by column )

--------按组给行分序号

关于Oracle取整的函数. .

关于Oracle取整的函数分别有以下几种:

　 1.取整(大)

　　select ceil(-1.001) value from dual

　　2.取整（小）

　　select floor(-1.001) value from dual

　　3.取整（截取）

　　select trunc(-1.002) value from dual

4.取整(舍入)

select round(-1.001) value from dual

生成自然数列：

select rownum

from daul

connect by rownum < 1000 ;

e.g:

select mod(rownum,50), rownum,rownum,rownum,rownum,rownum

from dual

connect by rownum<=10000

列合并：wmsys.wm_concat

select u_id, wmsys.wm_concat(goods || '(' || num || '斤)' ) goods_sum from shopping group by u_id

u_id goods_sum

____________________

1 苹果(2斤),西瓜(4斤),橘子(3斤)

2 梨子(5斤)

3 葡萄(1斤),香蕉(1斤