Question

mysql sql语句查询，每隔7天的数据

Answer 1

SELECT * FROM `tbl` WHERE id IN (
SELECT MAX(id) FROM `tbl`
WHERE createdat BETWEEN ADDDATE(DATE_FORMAT(NOW() ,"%Y-%m-%d"), INTERVAL -6 DAY) AND DATE_FORMAT(NOW(),'%Y-%m-%d')
GROUP BY DATE_FORMAT(createdat,'%Y-%m-%d')
)

前提你的表要有自增主键