select cast('' as datetime)
, cast(nullif('','') as datetime)
, isnull(cast(nullif('','') as datetime),getdate())
写到sql server的查询器中
根本看不出来你这sql写的是什么鬼https://www.cnblogs.com/pythonywy/p/11181249.html,https://www.cnblogs.com/pythonywy/p/11196859.html这两篇是原生sql语句只针对mysql数据库