mysql 比较字符串是否相等

使用 <=> 可以比较字符串  1是相同 0是不同  空字符串和Null 是不同的

代码 

select id ,stem <=> stem_260717, 
ques_analyze <=> ques_analyze_260717,   
answer <=> answer_260717, 
answer_keys <=> answer_keys_260717,
ques_option <=> ques_option_260717, grade_code,`type` from `jeecg-beta`.math_question  where 1=1 and   ( (ifnull(stem,'')  <=> ifnull(stem_260717,'')) != 1 or
(ifnull(ques_analyze,'') <=> ifnull(ques_analyze_260717,'')) != 1 or   
(ifnull(answer,'') <=> ifnull(answer_260717,'')) !=1 or 
(ifnull(answer_keys,'') <=> ifnull(answer_keys_260717,'')) !=1 or
(ifnull(ques_option,'') <=> ifnull(ques_option_260717,'')) !=1  ) and id = '6f7079760f8d4842be916a7800c1df9d'

 

结束