1. SELECT applicationId FROM `light_record`
2. where applicationId is not null
3. group by applicationId having count(applicationId) > 1 1. SELECT applicationId FROM `light_record`
2. where applicationId is not null
3. group by applicationId having count(applicationId) > 1 ![数据迁移方法数据迁移原则数据迁移之双写方案数据迁移之级联同步方案[图]](data:image/gif;base64,R0lGODlhAQABAIAAAP///wAAACwAAAAAAQABAAACAkQBADs=)