Question

我有以下脚本动态创建PostgreSQL数据库的视图。

CREATE OR REPLACE FUNCTION cs_refresh_mviews() RETURNS integer AS $$
DECLARE
    mviews RECORD;
    query text;
    park_name text;
    ppstatements int;
BEGIN
    RAISE NOTICE 'Creating views...';

    FOR mviews IN SELECT name FROM "Canadian_Parks" LOOP
        park_name := mviews.name;
        RAISE NOTICE 'Creating or replace view %s...', mviews.name; 
        query := 'CREATE OR REPLACE VIEW %_view AS
          SELECT * from "Canadian_Parks" where name=''%'';
          ALTER TABLE %_view OWNER TO postgres', park_name, park_name, park_name;
      --  RAISE NOTICE query;
        EXECUTE query;
    END LOOP;

    RAISE NOTICE 'Done refreshing materialized views.';
    RETURN 1;
END;
$$ LANGUAGE plpgsql;

我已确认字符串的完整性，例如

CREATE OR REPLACE VIEW Saguenay_St__Lawrence_view AS
SELECT * from "Canadian_Parks" where name='Saguenay_St__Lawrence';
ALTER TABLE Saguenay_St__Lawrence_view OWNER TO postgres

通过手动将其提交到数据库并获得成功响应来分配给查询变量。

但是，如果我尝试使用

执行该功能

SELECT cs_refresh_mviews();

显示以下错误：

ERROR:  query "SELECT 'CREATE OR REPLACE VIEW %_view AS SELECT * from "Canadian_Parks" where name=''%''; ALTER TABLE %_view OWNER TO postgres', park_name, park_name, park_name" returned 4 columns
CONTEXT:  PL/pgSQL function "cs_refresh_mviews" line 32 at assignment

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

ERROR: query "SELECT 'CREATE OR REPLACE VIEW %_view AS SELECT * from "Canadian_Parks" where name=''%''; ALTER TABLE %_view OWNER TO postgres', park_name, park_name, park_name" returned 4 columns
SQL state: 42601
Context: PL/pgSQL function "cs_refresh_mviews" line 32 at assignment

为什么将它转换为SELECT语句而不是纯CREATE？

Answer 1

你的设置非常扭曲。为什么要在表的复合类型中保存视图名称的一部分而不是将其保存在纯文本列中？

无论如何，它可以像这样工作：

设置匹配问题：

CREATE SCHEMA x;  -- demo in test schema
SET search_path = x;
CREATE TYPE mviews AS (id int, name text); -- composite type used in table

CREATE TABLE "Canadian_Parks" (name mviews);
INSERT INTO "Canadian_Parks"(name) VALUES
 ('(1,"canadian")')
,('(2,"islandic")');  -- composite types, seriously?

SELECT name, (name).* from "Canadian_Parks";

CREATE OR REPLACE FUNCTION cs_refresh_mviews()
  RETURNS int LANGUAGE plpgsql SET search_path = x AS  -- search_path for test
$func$
DECLARE
    _parkname text;
BEGIN

FOR _parkname IN SELECT (name).name FROM "Canadian_Parks" LOOP
   EXECUTE format('
      CREATE OR REPLACE VIEW %1$I AS
      SELECT * FROM "Canadian_Parks" WHERE (name).name = %2$L;
      ALTER TABLE %1$I OWNER TO postgres'
      , _parkname || '_view', _parkname);
END LOOP;

RETURN 1;

END
$func$;

SELECT cs_refresh_mviews();

DROP SCHEMA x CASCADE; -- clean up

重点

在执行带有执行的文本时，需要以防范 SQL注入。我使用标识符的format()函数和文字
我使用语法SELECT (name).name来应对您奇怪的设置并立即提取我们需要的name。
同样，VIEW需要阅读WHERE (name).name = ..才能在此设置中使用。
我删除了许多与问题无关的噪音。
拥有函数RETURN 1也可能毫无意义。只需使用RETURNS void定义函数即可。不过，我保留了它以匹配这个问题。

未解开的设置

应该如何：

CREATE SCHEMA x;
SET search_path = x;

CREATE TABLE canadian_parks (id serial primary key, name text);
INSERT INTO canadian_parks(name) VALUES ('canadian'), ('islandic');

SELECT * from canadian_parks;

CREATE OR REPLACE FUNCTION cs_refresh_mviews()
  RETURNS void LANGUAGE plpgsql SET search_path = x AS
$func$
DECLARE
    parkname text;
BEGIN

FOR parkname IN SELECT name FROM canadian_parks LOOP
   EXECUTE format('
      CREATE OR REPLACE VIEW %1$I AS
      SELECT * FROM canadian_parks WHERE name = %2$L;
      ALTER TABLE %1$I OWNER TO postgres'
      , parkname || '_view', parkname);
END LOOP;

END
$func$;

SELECT cs_refresh_mviews();

DROP SCHEMA x CASCADE;

Answer 2

您在分配表达式中误解了逗号的使用。它将query转换为数组（RECORD）而不是标量。使用连接：

park_name := quote_ident(mviews.name||'_view');
query := 'CREATE OR REPLACE VIEW '||park_name||' AS SELECT * from "Canadian_Parks" where name='||quote_literal(mviews.name)||'; ALTER TABLE '||park_name||' OWNER TO postgres';

PL / pgSQL在EXECUTE中创建或替换

2 个答案:

设置匹配问题：

重点

未解开的设置