ORACLE数据库中分组字符串相加

最新推荐文章于 2022-11-01 17:35:22 发布

hdl62402

最新推荐文章于 2022-11-01 17:35:22 发布

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分类专栏： Oracle 数据库文章标签： oracle 数据库 function insert parallel sql

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本文介绍了在Oracle数据库中实现字符串按分组相加的方法，包括使用PL/SQL过程、自定义聚合函数、分析函数及连接操作等多种技术手段。

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ORACLE数据库中分组字符串相加

来自 http://blog.oracle.com.cn/index.php/233877/viewspace-5271.html

引用

--该测试脚本可以直接运行

--现在想把数据库中数据按照固定字段分组相加，这里总结了三种方法。

--创建测试表、添加测试数据

Sql代码

create table test(id varchar2(10),mc varchar2(50));
insert into test values('1','11111');
insert into test values('1','22222');
insert into test values('2','11111');
insert into test values('2','22222');
insert into test values('3','11111');
insert into test values('3','22222');
insert into test values('3','33333');
commit;

create table test(id varchar2(10),mc varchar2(50));
insert into test values('1','11111');
insert into test values('1','22222');
insert into test values('2','11111');
insert into test values('2','22222');
insert into test values('3','11111');
insert into test values('3','22222');
insert into test values('3','33333');
commit;

--方法一：

Sql代码

set serveroutput on size 1000000
declare
union_mc varchar2(200);
begin
for cur_a in(select distinct id from test) loop
for cur_b in(select mc from test where id=cur_a.id) loop
union_mc:=union_mc||cur_b.mc;
end loop;
dbms_output.put_line(cur_a.id||chr(9)||union_mc);
union_mc := '';
end loop;
end;
/

set serveroutput on size 1000000
declare
union_mc varchar2(200);
begin
for cur_a in(select distinct id from test) loop
for cur_b in(select mc from test where id=cur_a.id) loop
union_mc:=union_mc||cur_b.mc;
end loop;
dbms_output.put_line(cur_a.id||chr(9)||union_mc);
union_mc := '';
end loop;
end;
/

--方法二：

Sql代码

CREATE OR REPLACE function link(v_id varchar2) return varchar2 is
union_mc varchar2(200);
begin
for cur in (select mc from test where id = v_id) loop
union_mc := union_mc || cur.mc;
end loop;
union_mc := rtrim(union_mc, 1);
return union_mc;
end;
select id,link(id) from test group by id;
/

CREATE OR REPLACE function link(v_id varchar2) return varchar2 is
  union_mc varchar2(200);
begin
  for cur in (select mc from test where id = v_id) loop
    union_mc := union_mc || cur.mc;
  end loop;
  union_mc := rtrim(union_mc, 1);
  return union_mc;
end;


select id,link(id) from test group by id;
/

--方法三：

/*从Oracle 9i开始，开发者可以创建用户自定义的合计函数，除了PL/SQL外，还可以使用任何Oralce所支持的语言（如C＋＋或者Java）来创建合计函数。TYPE头定义必须包含ODCIAggregateInitialize、ODCIAggregateIterate、ODCIAggregateMerge和ODCIAggregateTerminate这四个接口函数。*/

/*Initialize函数对数据组各个需要处理的字段各运行一次。自然的，我需要为每一个值准备一个新的清单，所以需要初始化持久变量list，这里初始化值为null。*/

/*Iterate函数处理返回的行，所以实际上是由它来创建返回的值的清单。先测试list是否为空，如果为空，就把list直接设置为所引入的value值；如果list变量非空，则给list添加一个逗号后再插入value值，list的最大允许字符数32767。*/

/*Terminate函数在数据组的每个行的感兴趣字段数据被处理后执行。在这个函数中我只需简单的返回清单变量即可。*/

/*Merge函数，用来返回成功标记的。*/

/*创建自己的合计函数扩展了Oracle统计和文本处理能力。*/

Sql代码

create or replace type t_cat as object
(
union_mc VARCHAR2(200),
static function ODCIAggregateInitialize(sctx IN OUT t_cat) return number,
member function ODCIAggregateIterate(self IN OUT t_cat,
value IN varchar2) return number,
member function ODCIAggregateTerminate(self IN t_cat,
returnValue OUT varchar2,
flags IN number)
return number,
member function ODCIAggregateMerge(self IN OUT t_cat, ctx2 IN t_cat)
return number
)
;
create or replace type body t_cat is static function ODCIAggregateInitialize(sctx IN OUT t_cat) return number is begin sctx := t_cat(''); return ODCIConst.Success; end;
member function ODCIAggregateIterate(self IN OUT t_cat, value IN varchar2) return number is begin self.union_mc := self.union_mc || value; return ODCIConst.Success; end;
member function ODCIAggregateTerminate(self IN t_cat, returnValue OUT varchar2, flags IN number) return number is begin returnValue := self.union_mc; return ODCIConst.Success; end;
member function ODCIAggregateMerge(self IN OUT t_cat, ctx2 IN t_cat) return number is begin return ODCIConst.Success; end; end;
/

create or replace type t_cat as object
(
  union_mc VARCHAR2(200),
  static function ODCIAggregateInitialize(sctx IN OUT t_cat) return number,
  member function ODCIAggregateIterate(self  IN OUT t_cat,
                                       value IN varchar2) return number,
  member function ODCIAggregateTerminate(self        IN t_cat,
                                         returnValue OUT varchar2,
                                         flags       IN number)
    return number,
  member function ODCIAggregateMerge(self IN OUT t_cat, ctx2 IN t_cat)
    return number
)
;

create or replace type body t_cat is static function ODCIAggregateInitialize(sctx IN OUT t_cat) return number is begin sctx := t_cat(''); return ODCIConst.Success; end;

member function ODCIAggregateIterate(self IN OUT t_cat, value IN varchar2) return number is begin self.union_mc := self.union_mc || value; return ODCIConst.Success; end;

member function ODCIAggregateTerminate(self IN t_cat, returnValue OUT varchar2, flags IN number) return number is begin returnValue := self.union_mc; return ODCIConst.Success; end;

member function ODCIAggregateMerge(self IN OUT t_cat, ctx2 IN t_cat) return number is begin return ODCIConst.Success; end; end;
/

/*如果你的Oracle服务器没有配置成支持并行处理的方式，可以去掉参数PARALLEL_ENABLE*/

Sql代码

create or replace function catstr(v_mc varchar2) return varchar2
PARALLEL_ENABLE
AGGREGATE USING t_cat;
/
select id, catstr(mc) from test group by id;

create or replace function catstr(v_mc varchar2) return varchar2
  PARALLEL_ENABLE
  AGGREGATE USING t_cat;
/

select id, catstr(mc) from test group by id;

方法四：

Sql代码

select id,
mc,
row_number() over(partition by id order by id) rn_by_id,
row_number() over(order by id) + id rn
from test;

select id,
       mc,
       row_number() over(partition by id order by id) rn_by_id,
       row_number() over(order by id) + id rn
  from test;

/*
利用分析函数，构造两列，做为连接的条件：按照id分组，RN-1等于PRIOR RN作为条件连接。
ID MC RN_BY_ID RN
---------- -------------------------------------------------- ---------- ----------
1 11111 1 2
1 22222 2 3
2 11111 1 5
2 22222 2 6
3 11111 1 8
3 22222 2 9
3 33333 3 10
*/

Sql代码

select id, ltrim(max(sys_connect_by_path(mc, ';')), ';') add_mc
from (select id,
mc,
row_number() over(partition by id order by id) rn_by_id,
row_number() over(order by id) + id rn
from test)
start with rn_by_id = 1
connect by rn - 1 = prior rn
group by id
order by id;

select id, ltrim(max(sys_connect_by_path(mc, ';')), ';') add_mc
  from (select id,
               mc,
               row_number() over(partition by id order by id) rn_by_id,
               row_number() over(order by id) + id rn
          from test)
 start with rn_by_id = 1
connect by rn - 1 = prior rn
 group by id
 order by id;

/*
另用sys_connect_by_path函数实现字符串的连接，把最左边的分号去掉，即得到我们想要的结果
ID ADD_MC
---------- --------------------------------------------------------------------------------
1 11111;22222
2 11111;22222
3 11111;22222;33333
*/

Sql代码

select * from test;

select * from test;

方法四的另一种写法

估计类似的写法还有很多，这个和上一个不同在于用的没有带有start with（filter功能）的connect，并借助level和first_value来实现。

Sql代码

SELECT distinct id,
ltrim(first_value(mc_add)
over(partition by id order BY l DESC),
';')
from (SELECT id, LEVEL l, sys_connect_by_path(mc, ';') mc_add
from (select id || rownum rn, id || rownum - 1 rn_small, id, mc
from test)
CONNECT BY PRIOR rn = rn_small);

SELECT distinct id,
                ltrim(first_value(mc_add)
                      over(partition by id order BY l DESC),
                      ';')
  from (SELECT id, LEVEL l, sys_connect_by_path(mc, ';') mc_add
          from (select id || rownum rn, id || rownum - 1 rn_small, id, mc
                  from test)
        CONNECT BY PRIOR rn = rn_small);

变换一下：（考虑id不是数字的情况）

Sql代码