如何在表格中对每年的月度基数进行分类

Question

嗨，我有三个表格列
vehicle_id int（11）auto_increment primary_key，
vehicle_reg_no varchar（100）not_null，
inp_datetime datetime not_null

我需要提取这些数据。
车辆注册号 | 1月 | 2月 | March ....... 12月 | 总计

到目前为止，我做了这个查询，但我没有得到预期的值。

SELECT COUNT(vehicle_master.vehicle_id)as countVal,
vehicle_master.vehicle_reg_no,
MONTHNAME(STR_TO_DATE(EXTRACT(MONTH FROM vehicle_master.inp_datetime),'%m'))as monthName
FROM vehicle_master
GROUP BY  vehicle_master.inp_datetime

Answer 1

我不确定你的架构，但从我所看到的你可以只是寻找这个：

SELECT DATE_FORMAT(vm01.inp_datetime,"%M") as monthName
, COUNT(*) as countVal
FROM vehicle_master vm
GROUP BY monthName

Month    | Count
------------------
January  |   10
February |   13
March    |    4
etc      |  etc

然而，我有点觉得这不是你想要做的事情，在这种情况下，这可能会给你一个想法（或者至少这会给你输出，因为你＆＃39 ; ve指定了上述内容）：

SELECT vm.vehicle_reg_no as `Vehicle Register Number`
, COUNT(mv01.*) as January
, COUNT(mv02.*) as February
, COUNT(mv03.*) as March
-- , COUNT(mv04.*) as etc
, COUNT(mv.*) as Total
FROM vehicle_master vm
LEFT JOIN vehicle_master vm01 on vm01.vehicle_id=vm.vehicle_id and vm01.vehicle_reg_no=vm.vehicle_reg_no and vm01.inp_datetime=vm.inp_datetime and DATE_FORMAT(vm01.inp_datetime,"%m") = "01"
LEFT JOIN vehicle_master vm02 on vm02.vehicle_id=vm.vehicle_id and vm02.vehicle_reg_no=vm.vehicle_reg_no and vm02.inp_datetime=vm.inp_datetime and DATE_FORMAT(vm02.inp_datetime,"%m") = "02"
LEFT JOIN vehicle_master vm03 on vm03.vehicle_id=vm.vehicle_id and vm03.vehicle_reg_no=vm.vehicle_reg_no and vm03.inp_datetime=vm.inp_datetime and DATE_FORMAT(vm03.inp_datetime,"%m") = "03" -- etc
GROUP BY vehicle_reg_no