SQL AVG 函数

--  SQL AVG 函数
-- AVG 函数返回值列的平均值,NULL值不包括在计算中
-- 语法
SELECT AVG (collumn_name) FROM table_name
-- 例子: redBagMoney 作为一个新字段显示出来
SELECT AVG (red_packet_amount) AS redBagMoney FROM vault_user_red_packet_log
-- 例子:显示出red_packet_amount 大于平均值的的user_id
SELECT user_id FROM vault_user_red_packet_log WHERE red_packet_amount>(SELECT AVG (red_packet_amount) FROM vault_user_red_packet_log)