oracle 空字符串 null 和各种判断当前字段是否为空

情况一:

select (case when trim('      ') is not null then 'not null' else 'is null' end) as age from dual;

输出结果：age： 'is null' 

情况二:删除trim()

select (case when '      ' is not null then 'is null' else 'not null' end) as age from dual;

输出结果：age： 'not  null' 

由以上测试可以得出今后的判断条件为:

if (trim(nvl(var_name_str,''))='')  then

         begin

           your operation;

         end;

 end if;