Sql_简单查询语句

查询字段不为空字符串。

select * from table_name where ziduan <> '';

查询字段不为null值。

select * from table_name where ziduan is not null;

查询某个字段值为null

select * from customers where cust_email is null;

查询某个字段为空或者是空字符串

select * from table_name where (ziduan = '' or ziduan is null);