Question

我在Postgres中有一个返回setof复合类型的函数。返回时我只能使用return next;但不能使用return query命令，为什么会这样做？

 CREATE TYPE return_type AS
   (paramname character varying,
    value character varying);

 CREATE OR REPLACE FUNCTION test(i_param1 character varying, i_param2 character varying)
      RETURNS SETOF return_type AS

    --this works just fine returning two rows
    r.paramname:='row1';
    r.value:='myvalue1';
    return next r;        
    r.paramname:='row1';
    r.value:='myvalue1';
    return next r;
    return;

    --  with this command I do not get a single row attached in the resultset
    return query
    select 'row1' as paraName,'myvalue1' as value
    UNION ALL
    select 'row2' as paraName,'myvalue2' as value;
    return;

Answer 1

这对我有用，即使在Postgres 8.4：

CREATE OR REPLACE FUNCTION test(i_param1 varchar, i_param2 varchar)
  RETURNS SETOF return_type AS
$func$
BEGIN
    RETURN QUERY
    SELECT 'row1'::varchar, 'myvalue1'::varchar
    UNION ALL
    SELECT 'row2','myvalue2';
END
$func$  LANGUAGE plpgsql;

由于类型不匹配，您的原始文件应仅返回异常。您需要强制字符串文字到匹配类型。另一方面，列别名与此无关：在函数体外部不可见。

SQL Fiddle

在复合类型的Postgres 9.0函数中使用返回查询

1 个答案: