PostgreSQL 9.3 : Return strings from function

Question

我有以下称为 pro() 的函数。我想通过联合所有两个 select 语句和产品输出从中返回字符串。

函数:pro()

我的尝试:

create or replace function pro()
returns varchar as

$$

declare
    sql varchar;
    q varchar;
begin
    sql := 'SELECT DISTINCT  CAST(COUNT(ProductNumber) as varchar) ||'' - Count of the product Number '' as Descp
        FROM product
        UNION ALL
        SELECT DISTINCT CAST(COUNT(ProductName) AS varchar) || '' - Count of the product Name '' as Descp
        FROM product';

    raise info '%',sql;

    execute sql into q;

    return q;

end;
$$

language plpgsql;

调用函数:

select pro();

这只返回 select 语句的第一部分:

 ______________________________________
|pro                                   |
|character varying                     |
|______________________________________|
|6 - Count of the product Number       |
|______________________________________|

但预期的结果应该是:

 ______________________________________
|pro                                   |
|character varying                     |
|______________________________________|
|6 - Count of the product Number       |
|______________________________________|
|6 - Count of the product Name         |
|______________________________________|

Answer 1

尝试使用这些函数:

使用plpgsql

create or replace function pro1()returns 
table ( 
       descp text
      )
as
$$
begin
    return QUERY execute (
         'SELECT DISTINCT  CAST(COUNT(product) as varchar) ||'' - Count of the product Number '' as Descp
         FROM product
         UNION ALL
         SELECT DISTINCT CAST(COUNT(productid) AS varchar) || '' - Count of the product Name '' as Descp
         FROM product');
end;
$$
language plpgsql;

或

使用sql

create or replace function pro2() returns table  ( descp text) 
as
$$
  SELECT DISTINCT  CAST(COUNT(product) as varchar) ||' - Count of the product Number ' as Descp
  FROM product
    UNION ALL
  SELECT DISTINCT CAST(COUNT(productid) AS varchar) || ' - Count of the product Name 'as Descp
  FROM product;
$$
language sql;