动态SQL查询文本

Question

您好有人可以告诉我什么，我搞乱了，我得到的错误。当在第一个SELECT子句中，这里是我的代码，我已经写了我对它进行更新：

CREATE OR REPLACE FUNCTION get_all_results() RETURNS VOID AS 
    $BODY$ 
    DECLARE 
    r RECORD; 
    BEGIN 


    FOR r IN (SELECT 'CREATE TRIGGER ' || tab_name|| '_if_modified_trg AFTER INSERT OR UPDATE OR DELETE ON ' || tab_name|| ' FOR EACH ROW WHEN (session_user <> ''source1'' OR (session_user = ''source1'' AND '|| tab_name ||' IN (SELECT*FROM table_names))) 
    EXECUTE PROCEDURE audit.if_modified_func(); ' 
     AS trigger_creation_query 
    FROM (
    SELECT table_name as tab_name 
    FROM information_schema.tables 
    WHERE table_schema='public' 
    AND table_type != 'VIEW' 

    ) AS foo WHERE tab_name||'_if_modified_trg' NOT IN (SELECT tgname from pg_trigger where not tgisinternal)) 


LOOP 


    EXECUTE r.trigger_creation_query; 


END LOOP; 


END 
$BODY$ 

LANGUAGE plpgsql; 
SELECT * FROM get_all_results(); 

Answer 1

从https://www.postgresql.org/docs/current/static/sql-createtrigger.html

在FOR EACH ROW触发器中，WHEN条件可以分别通过写入OLD.column_name或NEW.column_name来引用旧行和/或新行值的列。

这意味着你不能在触发条件中使用子查询。至少不在行触发器中。