PostgreSQL 动态表名问题求教

[nigdaemon]

我想创建一个函数，用来查询一个表里的数据，但是表名是需要动态变化的
函数大概的方法如下：
CREATE OR REPLACE FUNCTION test()
RETURNS SETOF record AS
$BODY$
begin
return query select dummy from dual;
end;
$BODY$
LANGUAGE 'plpgsql' VOLATILE;
ALTER FUNCTION test() OWNER TO admin;

我想让“dual”这个表名按照输入来定义，自己写了下面的方法：
CREATE OR REPLACE FUNCTION test(ff varchar)
RETURNS SETOF record AS
$BODY$
DECLARE
aa varchar;
begin
aa := "select dummy from "+ff;
execute aa;
end;
$BODY$
LANGUAGE 'plpgsql' VOLATILE;
ALTER FUNCTION test() OWNER TO admin;

但是执行以下语句时会报错：
select * from test(dual) as ok(dummy character varying);

ERROR: column "dual" does not exist
LINE 1: select * from test(dual) as ok(dummy character v.......

我对对PostgreSQL的语法不是很清楚，查了很多资料也没搞清楚动态SQL是怎么构造出来的
还请各位帮忙，小弟不胜感激！

[nigdaemon]

create table department(id int primary key, name text);


create or replace function GetRows(text) returns setof record as
'
declare
r record;
begin
for r in EXECUTE ''select * from '' || $1 loop
return next r;
end loop;
return;
end
'
language 'plpgsql';


select * from GetRows('Department') as dept(deptid int, deptname text);



这个是官方7.3文档里的例子 照样子写了以后 调用也报跟我一样的错误

[nigdaemon]

CREATE OR REPLACE FUNCTION test(ff varchar)
RETURNS SETOF record AS
$BODY$
DECLARE
aa varchar;
begin
aa := 'select dummy from '||ff;
execute aa;
end;
$BODY$
LANGUAGE 'plpgsql' VOLATILE;
ALTER FUNCTION test() OWNER TO admin;

已解决，看类似的看多了，引号搞错了。。。 连接符也混乱了。。

[wwwwb]

呵呵，自己解决更好

[ACMAIN_CHM]

[feixianxxx]