pl/pgsql 函数中的动态 SQL 语法错误

Question

我在 PostgreSQL 10 中使用 pl/pgsql 来创建复杂查询。我正在用几个 JOINs 和 ANDs 测试一个查询。这是我目前所拥有的：

DROP FUNCTION IF EXISTS search_person(name text);
CREATE  FUNCTION search_person(name text) RETURNS TABLE(address_id integer, address_geom text, event_name text) AS $$
--DECLARE 

BEGIN
    RETURN QUERY EXECUTE 
    'SELECT address.id, event.name, address.geom 
    FROM  event JOIN person JOIN address JOIN person_address JOIN event_person
    WHERE 
    person_address.event_id = event.id AND
    event_person.event_id = event.id AND
    person.id = event_person.person_id AND
    person.name like
    '        

    USING name;
END;
$$
LANGUAGE plpgsql;

我在创建这个函数时没有遇到任何错误。我这样称呼它 select search_person('nick'); 我得到：

ERROR:  syntax error at or near "WHERE"
LINE 3:     WHERE 
            ^
QUERY:  SELECT address.id, event.name, address.geom 
    FROM  event JOIN person JOIN address JOIN person_address JOIN event_person
    WHERE 
    person_address.event_id = event.id AND
    event_person.event_id = event.id AND
    person.id = event_person.person_id AND
    person.name like
    
CONTEXT:  PL/pgSQL function search_creator(text) line 5 at RETURN QUERY
SQL state: 42601

我看不到或无法解决问题。我尝试在 WHERE 子句中将 AND 替换为 ||，但没有任何改变。

我该怎么办？

编辑

这是我现在的代码，但根据我检查的数据库数据，我得到了一个空的 table，尽管我应该得到结果。

CREATE  FUNCTION search_person(name character(600)) RETURNS TABLE(address_id bigint, address_geom geometry, event_name character(200)) AS $$

BEGIN
    RETURN QUERY EXECUTE 
    'SELECT address.id, address.geom, event.name        

    FROM
    person 
    JOIN event_creator ON event_person.person_id = person.id
    JOIN event ON event.id = event_person.event_id 
    JOIN person_address ON person_address.event_id = event.id 
    JOIN address ON address.id = cep.address_id

    WHERE person.name LIKE '
    USING name;

END;
$$
LANGUAGE plpgsql;

Answer 1

创建 PL/pgSQL 函数时，函数体按原样 保存为字符串文字 。仅应用表面语法检查。包含的语句实际上并未在更深层次上执行或测试。

但是，在实际的 SQL 语句中仍会检测到查询字符串中的基本语法错误。但是你正在使用 dynamic SQL with EXECUTE。该语句包含在嵌套的字符串文字中，您自己负责。

这似乎从一开始就被误导了。动态 SQL 没有明显的原因。 （除非你的数据分布非常不均匀，并且想强制 Postgres 为每个输入值生成自定义计划。）

如果您使用了普通的 SQL 语句，您会在创建时收到错误消息：

CREATE OR REPLACE FUNCTION search_person(name text)  -- still incorrect!
  RETURNS TABLE(address_id integer, address_geom text, event_name text) AS
$func$
BEGIN
   RETURN QUERY
   SELECT address.id, event.name, address.geom 
   FROM  event JOIN person JOIN address JOIN person_address JOIN event_person
   WHERE 
   person_address.event_id = event.id AND
   event_person.event_id = event.id AND
   person.id = event_person.person_id AND
   person.name like ;  -- still , but refers to func param now!
END
$func$  LANGUAGE plpgsql;

SQL 语句仍然无效。 [INNER] JOIN requires a join condition - 。而且我根本看不到 PL/pgSQL 的必要性。一个简单的 SQL 函数 应该很好用：

CREATE FUNCTION search_person(name text)
  RETURNS TABLE(address_id integer, address_geom text, event_name text) AS
$func$
   SELECT a.id, a.geom, e.name  -- also fixed column order to match return type
   FROM   person         AS p
   JOIN   event_person   AS ep ON ep.person_id = p.id
   JOIN   event          AS e  ON e.id = ep.event_id
   JOIN   person_address AS pa ON pa.event_id = e.id
   JOIN   address        AS a  ON a.id = pa.address_id -- missing join condition !!
   WHERE  p.name LIKE ;
$func$  LANGUAGE sql;

我重写了查询以修复语法错误，使用 table 别名以提高可读性。最后，我还根据有根据的猜测添加了一个缺失的条件：a.id = pa.address_id.

现在应该可以了。

pl/pgsql 函数中的动态 SQL 语法错误

Syntax error in dynamic SQL in pl/pgsql function

sql

postgresql

dynamic-sql

plpgsql

where