mysql 查询json类型数据

先查询mysql的版本，如果mysql版本在5.7及以上版本可以使用json格式

select version()

如果 t1表里有一个extra字段，字段是text类型，数据为json格式 {"value":"XMjgxIqqqqqqqqqq"}

通过jSON_EXTRACT可以获取json里面value对于的值

JSON_EXTRACT(t1.extra,'$.value')

得到 "XMjgxIqqqqqqqqqq"

如果想去除两侧引号，需要先做类型转换再做trim

trim(both '"' from cast(JSON_EXTRACT(t1.extra,'$.value') as char))

得到 XMjgxIqqqqqqqqqq

原始sql和原始结果

select t1.id AS item_id, t1.title AS item_name,t6.id AS topic_id, 
       t6.title AS topic_name, t1.extra AS media_id, t1.biz_type 
        from tem t1
        join component_item t2 on t1.id = t2.item_id
        join component t3 on t2.component_id = t3.id
        join drawer t4 on t4.id = t3.drawer_id
        join channel_drawer t5 on t5.drawer_id = t4.id
        join channel t6 on t6.id = t5.channel_id
        where t1.biz_type in ("JUMP_TO_SHOW","JUMP_TO_VIDEO")
              and t1.extra IS NOT NULL 
              and t6.topic_property IS NOT NULL 

优化后的sql

select t1.id AS item_id, t1.title AS item_name,t6.id AS topic_id, 
       t6.title AS topic_name, trim(both '"' from cast(JSON_EXTRACT(t1.extra,'$.value') as char)) AS media_id, 
       trim(LEADING 'JUMP_TO_' from t1.biz_type) AS biz_type
        from item_pre t1
        join component_item_pre t2 on t1.id = t2.item_id
        join component_pre t3 on t2.component_id = t3.id
        join drawer_pre t4 on t4.id = t3.drawer_id
        join channel_drawer_pre t5 on t5.drawer_id = t4.id
        join channel_pre t6 on t6.id = t5.channel_id
        where t1.biz_type in ("JUMP_TO_SHOW","JUMP_TO_VIDEO")
              and t1.extra IS NOT NULL 
              and t6.topic_property IS NOT NULL
              and JSON_EXTRACT(t6.topic_property,'$.group')= "电影"