SQL查询的功能没有结果数据的目的地 [英] Function with SQL query has no destination for result data

问题描述

我正在尝试创建一个返回SELECTed结果集的函数. 当我像这样select * from tst_dates_func()调用我的postgres函数时，出现如下所示的错误:

I am trying to create a function that returns a SELECTed resultset. When I call my postgres function like this select * from tst_dates_func() I get an error as shown below:

ERROR:  query has no destination for result data
HINT:  If you want to discard the results of a SELECT, use PERFORM instead.
CONTEXT:  PL/pgSQL function "tst_dates_func" line 3 at SQL statement

********** Error **********

ERROR: query has no destination for result data
SQL state: 42601
Hint: If you want to discard the results of a SELECT, use PERFORM instead.
Context: PL/pgSQL function "tst_dates_func" line 3 at SQL statement

这是我创建的函数:

CREATE OR REPLACE FUNCTION tst_dates_func() 
    RETURNS TABLE( date_value date, date_id int, date_desc varchar) as
$BODY$   
BEGIN
    select a.date_value, a.date_id, a.date_desc from dates_tbl a;
END;
$BODY$
      LANGUAGE plpgsql;

我不确定为什么会出现上述错误.我想运行select * from tst_dates_func(); 并取回数据.或根据需要进一步加入结果集.这是什么问题?

I am not sure why I am getting the above error. I would like to run select * from tst_dates_func(); and get data back. Or further join the result set if needed. What is the problem here?

推荐答案

以纯SQL格式

CREATE OR REPLACE FUNCTION tst_dates_func() 
    RETURNS TABLE( date_value date, date_id int, date_desc varchar) as
$BODY$   
    select a.date_value, a.date_id, a.date_desc from dates_tbl a;

$BODY$
      LANGUAGE sql;

如果您确实需要plpgsql，请使用return query

If you really need plpgsql use return query

CREATE OR REPLACE FUNCTION tst_dates_func() 
    RETURNS TABLE( date_value date, date_id int, date_desc varchar) as
$BODY$   
BEGIN
    perform SELECT dblink_connect('remote_db');
    return query
    select a.date_value, a.date_id, a.date_desc from dates_tbl a;

END;
$BODY$
      LANGUAGE plpgsql;

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