mysql常用查询

多表联合查询
订单表，用户表，

SELECT FROM_UNIXTIME(order_create_time,'%Y-%m-%d') AS order_create_time,a.user_id,a.goods_id,a.order_class,a.order_amount,a.order_bv,b.user_grade,b.user_level,b.user_parent_id,a.user_directseller_id 
  FROM order a 
  LEFT JOIN user_base b 
  ON a.user_id=b.user_id 
  WHERE FROM_UNIXTIME(order_create_time,'%Y-%m-%d')='2021-04-19'
  ORDER BY b.user_level DESC

多表联合查询
订单表，用户表，GROUP_CONCAT(b.order_id) AS order_id，按照user_level字段分组GROUP BY ，HAVING COUNT分组大于3

SELECT a.regtime,b.order_bv,b.user_directseller_id,GROUP_CONCAT(b.order_id) AS order_id
  FROM user_base a
  LEFT JOIN order b
  ON a.user_id=b.user_directseller_id
  WHERE a.user_grade='3' AND a.regtime>'1618813834' AND b.t31_s='0'
  GROUP BY b.user_level HAVING COUNT(*)>=3

时间格式，datetime

SELECT * FROM `order_base` WHERE DATE_FORMAT(order_create_time,'%Y-%m')='2021-03'

时间格式，int  unix时间戳

SELECT * FROM `order_base` WHERE FROM_UNIXTIME(order_create_time,'%Y-%m')='2021-03'

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