PostgreSQL 存储过程

-- Function: tms_org_score_statis()

-- DROP FUNCTION tms_org_score_statis();

CREATE OR REPLACE FUNCTION tms_org_score_statis()
  RETURNS character varying AS
$BODY$

declare 
r record;
statis_sql "varchar";
execute_sql "varchar";
num int4 := 0;
total_score numeric(10,2);
begin
statis_sql := 'select tms.* from 
(SELECT ORG.ID ORG_ID, COALESCE(AB.participation_legal, 0) participation_legal, COALESCE(AB.participation_leader, 0) participation_leader, 
COALESCE(AB.participation_cadre, 0) participation_cadre, COALESCE(GH.participation_staff, 0) participation_staff,
COALESCE(AB.qualified_legal, 0) qualified_legal, COALESCE(AB.qualified_leader, 0) qualified_leader, COALESCE(AB.qualified_cadre, 0)qualified_cadre, 
COALESCE(GH.qualified_staff, 0) qualified_staff, COALESCE(GH.avg_answer_time, 0) avg_answer_time,
CASE WHEN TSC.ORG_ID > 0 THEN TRUE ELSE FALSE END AS EXIST
 FROM PUBLIC.T_ORG ORG
 LEFT OUTER JOIN 
(
SELECT BB.ORG_ID, 
SUM(participation_legal) participation_legal, 
SUM(participation_leader) participation_leader, 
SUM(participation_cadre) participation_cadre, 
SUM(qualified_legal) qualified_legal, 
SUM(qualified_leader) qualified_leader, 
SUM(qualified_cadre) qualified_cadre
FROM 
(
	SELECT AA.ORG_ID, 
	CASE WHEN AA.ROLE_ID = 1 THEN 5 ELSE 0 END AS participation_legal,
	CASE WHEN AA.ROLE_ID = 2 THEN 3 ELSE 0 END AS participation_leader, 
	CASE WHEN AA.ROLE_ID = 3 THEN 2 ELSE 0 END AS participation_cadre, 
	CASE WHEN AA.ROLE_ID = 1 AND AA.AR = 10 THEN 5 ELSE 0 END AS qualified_legal,
	CASE WHEN AA.ROLE_ID = 2 AND AA.AR = 10 THEN 3 ELSE 0 END AS qualified_leader,
	CASE WHEN AA.ROLE_ID = 3 AND AA.AR = 10 THEN 2 ELSE 0 END AS qualified_cadre
	FROM 
	(
	SELECT US.ORG_ID, UR.ROLE_ID, MIN(ANSWER_RESULT) AR
	FROM PUBLIC.T_USER US 
	LEFT OUTER JOIN PUBLIC.T_USER_ROLE UR 
	ON US.ID = UR.USER_ID 
	LEFT OUTER JOIN PUBLIC.T_QUESTION_PAPER QP 
	ON US.ID = QP.USER_ID 
	where ur.role_id in (1, 2, 3)
	GROUP BY US.ORG_ID, UR.ROLE_ID 
	) AA
) BB
GROUP BY BB.ORG_ID
) AB
ON ORG.ID = AB.ORG_ID
left outer JOIN 
(
select org_id, (all_real_qty::numeric * 30 / (participator_qty)) participation_staff,
(total_SCORE / all_real_qty) * 0.5 qualified_staff, total_answer_time / all_real_qty avg_answer_time 
from 
(
SELECT ORG_ID, COUNT(*) all_real_qty,MIN(participator_qty) participator_qty, 
SUM(COALESCE(QP.score,0)) total_SCORE, COALESCE(sum(extract(epoch from (END_TIME - START_TIME))), 0) total_answer_time
FROM PUBLIC.V_USER_INFO VI
LEFT OUTER JOIN PUBLIC.T_QUESTION_PAPER QP
ON VI.USER_ID = QP.USER_ID
GROUP BY ORG_ID
) GG
) GH
ON ORG.ID = GH.ORG_ID
LEFT OUTER JOIN PUBLIC.t_competition_score TSC
ON ORG.ID = TSC.ORG_ID
) tms';

for r in execute statis_sql loop
	total_score := r.participation_legal + r.participation_leader + r.participation_cadre + r.participation_staff + r.qualified_legal + r.qualified_leader + r.qualified_cadre + r.qualified_staff;
	num := num + 1;

	IF R.EXIST = false THEN
	
	execute_sql := 'insert into public.t_competition_score(org_id,participation_legal,participation_leader, participation_cadre, participation_staff,
	qualified_legal,qualified_leader,qualified_cadre,qualified_staff,avg_answer_time, total_score,create_time,status,last_update_time) values
	(' || r.org_id || ',' || r.participation_legal || ',' || r.participation_leader || ',' || r.participation_cadre || ',' || r.participation_staff || ',' ||
	r.qualified_legal || ',' || r.qualified_leader || ',' || r.qualified_cadre || ',' || r.qualified_staff || ',' || r.avg_answer_time || ',' || 
	total_score || ', ''' || now() || ''',' || 20 || ',''' || now() || ''')';
	
	END IF;
	IF R.EXIST = true THEN 
	execute_sql := 'UPDATE public.t_competition_score set participation_legal = ' || r.participation_legal || ', participation_leader = ' || r.participation_leader || ', participation_cadre = '
	|| r.participation_cadre || ', participation_staff = ' || r.participation_staff || ', qualified_legal = ' || r.qualified_legal || ', qualified_leader = ' || r.qualified_leader
	|| ', qualified_cadre = ' || r.qualified_cadre || ', qualified_staff = ' || r.qualified_staff || ', avg_answer_time = ' || r.avg_answer_time || ', total_score = ' || total_score
	|| ', last_update_time = ''' || now() || ''' where org_id = ' || r.org_id;
	END IF;
	RAISE NOTICE '%', 'sql: ' || execute_sql;
	EXECUTE execute_sql;
end loop;
RETURN num;
END;
$BODY$
  LANGUAGE plpgsql VOLATILE
  COST 100;

perform org_id from t_competition_score where org_id = 1;

if found then 

raise notice 't';

else 

raise notice 'f';

end if;

CREATE TABLE message
(
id int8 NOT NULL,
receiveuserid int8,
senduserid int8,
receivedelete bool DEFAULT false,
senddelete bool DEFAULT false,
……
CONSTRAINT usermessage_pkey PRIMARY KEY (id)
)
略去其他字段，senduserid是发信息的用户id，senddelete如为true则表示这条消息被发信人所删除；至于receive我就不用说了。一条信息只有被发信人和收信人都删除，才能真正从表里删除（这是显然的，否则收信人删了一条消息后，发信人的“发件箱”里就会找不到这条消息）。
所以删除消息（可能是多条消息）的时候要进行各种判断（是否是发信人？是否是收信人？是否真正删除？），用单条SQL语句完成这个工作显然有些困难（当然用循环嵌套select不考虑效率的话也是可以实现的），只好写存储过程了。
顺便介绍常用的PL/pgSQL结构和语法吧：

• 结构

  PL/pgSQL是一种块结构的语言，比较方便的是用pgAdmin III新建Function，填入一些参数就可以了。基本上是这样的：

  CREATE OR REPLACE FUNCTION 函数名(参数1，[整型 int4, 整型数组 _int4, …])
  RETURNS 返回值类型 AS
  $BODY$
  DECLARE
  变量声明
  BEGIN
  函数体
  END;
  $BODY$
  LANGUAGE ‘plpgsql’ VOLATILE;

• 变量类型

  除了postgresql内置的变量类型外，常用的还有 RECORD ，表示一条记录。

• 赋值

  赋值和Pascal有点像：“变量 := 表达式;”
  有些奇怪的是连接字符串的是“||”，比如 sql := ‘SELECT * FROM’ || table || ‘WHERE …’;

• 判断

  判断又和VB有些像：
  IF 条件 THEN
  …
  ELSEIF 条件 THEN
  …
  ELSE
  …
  END IF;

• 循环

  循环有好几种写法：
  WHILE expression LOOP
  statements
  END LOOP;
  还有常用的一种是：（从1循环到9可以写成FOR i IN 1..9 LOOP）
  FOR name IN [ REVERSE ] expression .. expression LOOP
  statements
  END LOOP;

• 其他

  还有几个常用的函数：
  SELECT INTO record …; 表示将select的结果赋给record变量（RECORD类型）
  PERFORM query; 表示执行query并丢弃结果
  EXECUTE sql; 表示执行sql语句，这条可以动态执行sql语句（特别是由参数传入构造sql语句的时候特别有用）

最后，贴出解决上面这个问题的存储过程吧：

1. CREATE OR REPLACE FUNCTION message_deletes(ids "varchar", userid int8)
2.   RETURNS int4 AS
3. $BODY$
4. DECLARE
5.   r RECORD;
6.   del bool;
7.   num int4 := 0;
8.   sql "varchar";
9. BEGIN
10.   sql := 'select id,receiveuserid,senduserid,senddelete,receivedelete from message where id in (' || ids || ')';
11.   FOR r IN EXECUTE sql LOOP
12.     del := false;
13.     IF r.receiveuserid=userid and r.senduserid=userid THEN
14.       del := true;
15.     ELSEIF r.receiveuserid=userid THEN
16.       IF r.senddelete=false THEN
17.         update message set receivedelete=true where id = r.id;
18.       ELSE
19.         del := true;
20.       END IF;
21.     ELSEIF r.senduserid=userid THEN
22.       IF r.receivedelete=false THEN
23.         update message set senddelete=true where id = r.id;
24.       ELSE
25.         del := true;
26.       END IF;
27.     END IF;
28.     IF del THEN
29.       delete from message where id = r.id;
30.       num := num + 1;
31.     END IF;
32.   END LOOP;
33.   return num;
34. END;
35. $BODY$
36.   LANGUAGE 'plpgsql' VOLATILE;