Question

我创建了一个函数，并在函数内部使用了预定义的函数array_to_string。尝试执行功能时，出现以下错误。

ERROR:  function array_to_string(integer, unknown) does not exist
LINE 1: SELECT array_to_string(id, ',') FROM ame.stops where custome...
               ^
HINT:  No function matches the given name and argument types. You might need to add explicit type casts.
QUERY:  SELECT array_to_string(id, ',') FROM ame.stops where customer_id=customer_id and driver_id=driver_id
CONTEXT:  PL/pgSQL function ame.fn_get_stopids(integer,integer) line 4 at SQL statement
SQL state: 42883

当我在array_to_string语句中使用select时，效果很好。

select array_to_string(array(SELECT id FROM ame.stops where customer_id='31' and driver_id='770'), ', ')

功能代码

CREATE OR REPLACE FUNCTION ame.fn_Get_StopIds(customer_id integer, driver_id  integer) 
RETURNS text AS $$
DECLARE StopIds text;
BEGIN
    SELECT array_to_string(id, ',') FROM ame.stops where customer_id=customer_id and driver_id=driver_id into StopIds;
    RETURN StopIds;
END;
$$ LANGUAGE plpgsql;

Answer 1

该函数需要一个数组，但是您正在传递一个整数（id）。

在尝试工作时，您首先要将id转换为数组。

您可能想先使用array_agg

构建阵列

SELECT array_to_string(array_agg(id), ',') 
FROM ame.stops 
where customer_id=customer_id and driver_id=driver_id 
into StopIds;

但是您不需要构建和连接数组，只需执行

SELECT string_agg(id::text, ',') 
FROM ame.stops 
where customer_id=customer_id and driver_id=driver_id 
into StopIds;

您可能想按ID订购

Answer 2

CREATE OR REPLACE FUNCTION ame.fn_get_stopids
                           (_customer_id integer,
                            _driver_id  integer) 
RETURNS text AS
$$
DECLARE
  stopids text;
BEGIN
  SELECT string_agg(id::text, ',') INTO stopids;
         FROM ame.stops
         WHERE customer_id = _customer_id 
               AND driver_id = _driver_id
  RETURN stopids;
END;
$$
LANGUAGE plpgsql;

出现错误-没有函数与给定的名称和参数类型匹配。在Postgres

2 个答案: