mysql有json类型。MySQL从5.7版本开始，引入了JSON数据类型，可以直接操作json数据；但MySQL5.7版本以下，在表中保存JSON格式类型的数据，则需要依靠varchar或者text之类的数据类型。

MySQL中的JSON类型

json是一个非常好用的数据类型，在mysql5.7之前人们都是用string来储存json的，但是这样有个问题就是不能操作json，5.7以后就可以直接操作json数据了。

创建没什么好说的就是json 不用带长度默认为0更新 、和插入可以用string插入查询、个人不喜欢把数据交给后台处理，那就交给数据库处理吧例子如下：数据库某张表有个content_json字段，里面有这样的数据！

{"bill": [{"bill": [{"id": "C81AEAD03F90000142E81B405F6FADC0","uuid": "cfd872541b3b4507a50c2b2eda6bef28","billid": "kjdzyljgmzsfzypj","pageno": [],"billver": "V1","billname": "新增测试","fjNumber": "","trueName": "","allPageno": [{"top": 13,"left": 7}],"billValue": {},"isOtherZL": "","billNumber": "","fjTMNumber": ""},{"id": "C81AED69D6400001A07818551D9EBEC0","uuid": "05d87c8052cd44209c684407d200b7ec","billid": "opztsfpsgd","pageno": [],"billver": "V1","billname": "发票申购","fjNumber": "","trueName": "","allPageno": [{"top": 13,"left": 7}],"isOtherZL": "","billNumber": "","fjTMNumber": ""}],"index": "","dependBjBill": {"formula": "","keyView": ""},"codeCondition": {"formula": "","keyView": ""},"billRuleCondition": {"formula": "","keyView": ""}},{"bill": [{"id": "C81AED84903000019B29EAB0196014CE","uuid": "0d93fe614d09489cbad8fa5a3d160289","billid": "kjdzcwgwht","pageno": [],"billver": "V1","billname": "财务顾","fjNumber": "","trueName": "","allPageno": [{"top": 39,"left": 7}],"isOtherZL": "","billNumber": "","fjTMNumber": ""}],"index": "","dependBjBill": {"formula": "","keyView": ""},"codeCondition": {"formula": "","keyView": ""},"billRuleCondition": {"formula": "","keyView": ""}}],"questions": [],"relyonCondition": {}}

结构是这样的，我们要查询最底层uuid！按条件查bill下是一个数组 里面的bill还是一个数组那么要查最底层的uuid怎么查呢？
；
个人更喜欢用类似lambda这种方法毕竟这是一个有逼格又好看的操作：

SELECT content_json->'$.bill[*].bill[*].uuid' fromb WHERE JSON_CONTAINS(content_json->'$.bill[*].bill[*].uuid' ,'["cfd872541b3b4507a50c2b2eda6bef28"]')

查询结果

代码分析：
content_json->’$.bill[].bill[].uuid’ ；

表示content_json字段
"$"是必须符号 点代表对象
*代表全部

那么代码意思就是查询content_json字段里面全部bill（第一个）中全部bill（第二个）的uuid组成一个数组返回；
where后面跟着的条件的意思是 存在某个值 这个值可以是一个也可以是多个
JSON_CONTAINS（字段，参数）；
字段必须是要查的指定值如 content_json->’$.bill[].bill[].uuid’ ；
参数必须是json类型 string是不行的。