ai网站大全,找网站公司制作网站,网站代码设计,网站的开发流程分为PostgreSQL空值的判断 空值判断非空判断总结 空值判断
-- 查询为空的 is null,sql简写isnull
select * from employees where manager_id isnull;select * from employees where manager_id is null;非空判断
-- 查询不为空的 is not null;sql简写notnull
select * from empl… PostgreSQL空值的判断 空值判断非空判断总结 空值判断
-- 查询为空的 is null,sql简写isnull
select * from employees where manager_id isnull;select * from employees where manager_id is null;非空判断
-- 查询不为空的 is not null;sql简写notnull
select * from employees where manager_id is not null;
select * from employees where manager_id notnull;总结
