oracle wsywmsys.wm_concat() 妙用

(查找函数时找到. copy过来记录一下.  源地址:http://blog.csdn.net/yy_mm_dd/article/details/3182953)

wmsys.wm_concat这个函数很有用，它的作用是以',' 链接字符

示例如下. 创建数据表.

create table idtable (id number,name varchar2(30));



insert into idtable values(10,'ab');

insert into idtable values(10,'bc');

insert into idtable values(10,'cd');

insert into idtable values(20,'hi');

insert into idtable values(20,'ij');

insert into idtable values(20,'mn');

查询如下
1.

 select * from idtable;         ID NAME
---------- ------------------------------
        10 ab
        10 bc
        10 cd
        20 hi
        20 ij
        20 mn
2.
select id,wmsys.wm_concat(name) name from idtable        ID NAME
---------- --------------------------------------------------------------------------------
        10 ab,bc,cd
        10 ab,bc,cd
        10 ab,bc,cd
        20 ab,bc,cd,hi,ij,mn
        20 ab,bc,cd,hi,ij,mn
        20 ab,bc,cd,hi,ij,mn 3.
select id,wmsys.wm_concat(name) over (order by id,name) name from idtable;        ID NAME
---------- --------------------------------------------------------------------------------
        10 ab
        10 ab,bc
        10 ab,bc,cd
        20 ab,bc,cd,hi
        20 ab,bc,cd,hi,ij
        20 ab,bc,cd,hi,ij,mn4.select id,wmsys.wm_concat(name) over (partition by id) name from idtable;        ID NAME
---------- --------------------------------------------------------------------------------
        10 ab,bc,cd
        10 ab,bc,cd
        10 ab,bc,cd
        20 hi,ij,mn
        20 hi,ij,mn
        20 hi,ij,mn
5.
select id,wmsys.wm_concat(name) over (partition by id,name) name from idtable;        ID NAME
---------- --------------------------------------------------------------------------------
        10 ab
        10 bc
        10 cd
        20 hi
        20 ij
        20 mn