oracle 空字符串 null 和各类判断当前字段是否为空

状况一: 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'  状况二:删除trim() select (case when '      ' is not null then 'is null' else 'no

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