Postgres if语句里面的函数插入值

Question

可以使这个函数有效吗？我在Postgres函数的Insert Into查询中有If语句。

你有什么方法？

CREATE FUNCTION proc_api_consumer_audit_insert() 
    RETURNS TRIGGER AS $api_consumer$ 
    BEGIN 
     INSERT INTO api_consumer_audit(api_consumer_id, change_type, changed_by, changed_date, business_id_old, business_id_new, name_old, name_new, api_callback_url_old, api_callback_url_new, application_base_url_old, application_base_url_new, authorization_callback_url_old, authorization_callback_url_new, status_old, status_new) 
     VALUES(NEW.id, 'INSERT', (IF NEW.created_by=null THEN CURRENT_USER ELSE NEW.created_by END IF;), CURRENT_TIMESTAMP, null, NEW.business_id, null, NEW.name, null, NEW.api_callback_url, null, NEW.application_base_url, null, NEW.authorization_callback_url, null, NEW.status); 
     RETURN NEW; 
    END; 
    $api_consumer$ LANGUAGE plpgsql; 

Answer 1

SQL中没有IF。在一般人会使用CASE表达，但在你的情况coalesce()要短得多：

INSERT INTO api_consumer_audit(...) 
VALUES (NEW.id, 
     'INSERT', 
     coalesce(new.created_by, current_user), 
     ...); 

与CASE表达式同样会是这样的：

INSERT INTO api_consumer_audit(...) 
VALUES (NEW.id, 
     'INSERT', 
     case 
      when new.created_by IS NOT NULL then new.created_by 
      else current_user 
     end, 
     ...);