oracle中替代wm_concat函数的方法

racle数据库中，不许用wm_concat函数，合并列，希望得到与wm_concat 一样的结果: s_type  s2 水果    葡萄,哈密瓜,香瓜,火龙果 蔬菜    西兰花,茼蒿,茄子 坚果    核桃,巴旦木

数据如下： create table t_thz_1(   n_id number(10),   s_mc varchar2(100),   s_type varchar2(10) );

truncate table t_thz_1;

insert into t_thz_1(n_id,s_mc,s_type)

select 1 n_id,'葡萄' s_mc,'水果' s_type from dual union all

select 2 n_id,'哈密瓜' s_mc,'水果' s_type from dual union all

select 3 n_id,'西兰花' s_mc,'蔬菜' s_type from dual union all

select 4 n_id,'核桃' s_mc,'坚果' s_type from dual union all select 5 n_id,'茼蒿' s_mc,'蔬菜' s_type from dual union all

select 6 n_id,'香瓜' s_mc,'水果' s_type from dual union all select 7 n_id,'巴旦木' s_mc,'坚果' s_type from dual union all

select 8 n_id,'茄子' s_mc,'蔬菜' s_type from dual union all select 10 n_id,'火龙果' s_mc,'水果' s_type from dual ;

commit;

-----------------------方法一------------------------------------------------------------

11g及以上用这个函数 LISTAGG

select s_type,listagg(s_mc,'，') within group (order by n_id) mc from t_thz_1
group by s_type
;

如果是低版本的话可以参考以下方法：

第一步（创建类型）：

 CREATE OR REPLACE TYPE tab_str IS TABLE OF VARCHAR2(4000);

第二步（创建函数）：

 1 CREATE OR REPLACE FUNCTION fn_to_str(  2   p_str_tab IN tab_str,  3   p_separator IN VARCHAR2 DEFAULT ','  4 )  5 RETURN VARCHAR2 IS  6   v_ret_str VARCHAR2(4000);  7 BEGIN  8   FOR i IN 1..p_str_tab.COUNT LOOP  9     v_ret_str:=v_ret_str||p_separator||p_str_tab(i); 10   END LOOP; 11   RETURN v_ret_str; 12 END fn_to_str;

第三步（利用前两步创建的类型和函数及 COLLECT 函数来查询，collect是在Oracle 10g中新增加了一个聚合函数）：

SELECT t.s_type,LTRIM(fn_to_str(CAST(COLLECT(t.s_mc) AS tab_str)),',') s_names FROM demo.t_thz_1 t GROUP BY t.s_type;

查询结果如下：

S_TYPE     S_NAMES

坚果       核桃,巴旦木

蔬菜       西兰花,茼蒿,茄子

水果       葡萄,哈密瓜,火龙果,香瓜

-----------------------方法二------------------------------------------------------------ 如果值不多,也可以用case when这样写:

select s_type,substr(pt||hmg||xg||hlg||xlh||th||qz||ht||bdm,2) as s_mc from ( select s_type, max(case when s_mc='葡萄' then ','||s_mc end) as pt, max(case when s_mc='哈密瓜' then ','||s_mc end) as hmg, max(case when s_mc='香瓜' then ','||s_mc end) as xg, max(case when s_mc='火龙果' then ','||s_mc end) as hlg, max(case when s_mc='西兰花' then ','||s_mc end) as xlh, max(case when s_mc='茼蒿' then ','||s_mc end) as th, max(case when s_mc='茄子' then ','||s_mc end) as qz, max(case when s_mc='核桃' then ','||s_mc end) as ht, max(case when s_mc='巴旦木' then ','||s_mc end) as bdm   from t_thz_1 t   group by s_type  )