在存储过程 postgres 中创建自定义列

Question

我正在使用存储过程来 return 在我的大学注册的学生类型。将他们的 ID 推送到将要创建的新列中 return 他们的名字和姓氏（例如：通勤者、雇员、居民）。我一直收到错误消息：

ERROR:  syntax error at or near "if"
LINE 8:     if exists (select count(commuterid) > 0 from commuter wh...).

有什么建议或想法吗？

create or replace function roleAtMarist(int, REFCURSOR) returns refcursor as
$$
declare
   identifier      int := ;
   resultset refcursor := ;
 begin
  open resultset for
    if exists (select count(commuterid) > 0 from commuter where commuterid = identifier) then
      select fname, lname, "Commuter" as Role
      from people 
      where peopleid = identifier;
    end if;

    if exists (select count(employeeid) > 0 from employee where emplpoyeeid = identifier) then
      select fname, lname, "Employee" as Role
      from people 
      where peopleid = identifier;
    end if;

    if exists (select count(residentid) > 0 from studentpark where residentid = identifier) then
      select fname, lname, "Resident" as Role
      from people 
      where peopleid = identifier;
    end if;
return resultset;
end; 
$$
language plpgsql; 
select roleAtMarist(12, 'resultset') ;
fetch all from results ;

Answer 1

这在很多方面都是倒退的。游标将使用有效的 SQL 而不是 plpgsql 命令。但是您不需要游标，也不需要 plpgsql 开始。一个简单的 SQL 函数应该做：

CREATE OR REPLACE FUNCTION role_at_marist(_identifier int)
  RETURNS TABLE (fname text, lname text, "role" text) AS
$func$
   SELECT p.fname, p.lname, text 'Commuter'
   FROM   people 
   WHERE  p.peopleid = 
   AND    EXISTS (SELECT 1 FROM commuter c WHERE c.commuterid = p.peopleid)

   UNION ALL
   SELECT p.fname, p.lname, 'Employee'
   FROM   people 
   WHERE  p.peopleid = 
   AND    EXISTS (SELECT 1 FROM employee e WHERE e.emplpoyeeid = p.peopleid)

   UNION ALL
   SELECT p.fname, p.lname, 'Resident'
   FROM   people 
   WHERE  p.peopleid = 
   AND    EXISTS (SELECT 1 FROM studentpark s WHERE s.residentid = p.peopleid)
$func$ LANGUAGE sql;

致电：

SELECT * FROM role_at_marist(12);

集合返回函数可以像 FROM 列表中的表一样使用。
字符串文字用单引号括起来！

在存储过程 postgres 中创建自定义列

Creating Custom columns in stored procedure postgres

sql

database

postgresql

stored-procedures

plpgsql