MySQL 打印本月日历
备注:测试数据库版本为MySQL 8.0
文章目录
- 一. 需求:
- 二.解决方案
-
- 2.1 MySQL 8.0写法
- 2.2 MySQL8.0之前写法
一. 需求:
为当前月创建一个日历。日历的格式应该与书桌上的日历相似，通常情况下包含7列、5行。
二.解决方案
每个解决方案看起来都有所不同，但他们都采用了同样方式来解决问题:
返回当前月的每一天，然后依据当前月中每周的周内日期创建日历。
日历可采用不同的格式。例如Unix的call命令采用从星期日到星期六的格式。
本例都以ISO周序号为基准，因此采用了星期一到星期五的格式最方便。
一旦习惯了这种解决方案，就会明白，无论怎么重新定义格式都是非常简单的事，只需修改由ISO周规定的值即可。
2.1 MySQL 8.0写法
with RECURSIVE c(n) as
-- 构造一个1-40的临时表
(select 1 union all select n + 1 from c where n < 40),
-- 求出本月的第一天
firstday AS
( SELECT adddate(current_date,-dayofmonth(current_date)+1) fd),
-- 求出本月的每个日期及星期数
y AS
(
SELECT adddate(fd,c.n -1) yd,
dayofweek(adddate(fd,c.n -1)) wk,
month(adddate(fd,c.n -1)) mth,
weekofyear(adddate(fd,c.n -1)) yk
from c,firstday
where month(adddate(fd,c.n -1)) = month(fd)
)
SELECT max(case when wk = 2 then DATE_FORMAT(yd,'%d') else null end) Mo,
max(case when wk = 3 then DATE_FORMAT(yd,'%d') else null end) Tu,
max(case when wk = 4 then DATE_FORMAT(yd,'%d') else null end) We,
max(case when wk = 5 then DATE_FORMAT(yd,'%d') else null end) Th,
max(case when wk = 6 then DATE_FORMAT(yd,'%d') else null end) Fr,
max(case when wk = 7 then DATE_FORMAT(yd,'%d') else null end) Sa,
max(case when wk = 1 then DATE_FORMAT(yd,'%d') else null end) Su
from y
group by yk
测试记录:
mysql> with RECURSIVE c(n) as
-> -- 构造一个1-40的临时表
-> (select 1 union all select n + 1 from c where n < 40),
-> -- 求出本月的第一天
-> firstday AS
-> ( SELECT adddate(current_date,-dayofmonth(current_date)+1) fd),
-> -- 求出本月的每个日期及星期数
-> y AS
-> (
-> SELECT adddate(fd,c.n -1) yd,
-> dayofweek(adddate(fd,c.n -1)) wk,
-> month(adddate(fd,c.n -1)) mth,
-> weekofyear(adddate(fd,c.n -1)) yk
-> from c,firstday
-> where month(adddate(fd,c.n -1)) = month(fd)
-> )
-> SELECT max(case when wk = 2 then DATE_FORMAT(yd,'%d') else null end) Mo,
-> max(case when wk = 3 then DATE_FORMAT(yd,'%d') else null end) Tu,
-> max(case when wk = 4 then DATE_FORMAT(yd,'%d') else null end) We,
-> max(case when wk = 5 then DATE_FORMAT(yd,'%d') else null end) Th,
-> max(case when wk = 6 then DATE_FORMAT(yd,'%d') else null end) Fr,
-> max(case when wk = 7 then DATE_FORMAT(yd,'%d') else null end) Sa,
-> max(case when wk = 1 then DATE_FORMAT(yd,'%d') else null end) Su
-> from y
-> group by yk;
+------+------+------+------+------+------+------+
| Mo | Tu | We | Th | Fr | Sa | Su |
+------+------+------+------+------+------+------+
| NULL | NULL | NULL | 01 | 02 | 03 | 04 |
| 05 | 06 | 07 | 08 | 09 | 10 | 11 |
| 12 | 13 | 14 | 15 | 16 | 17 | 18 |
| 19 | 20 | 21 | 22 | 23 | 24 | 25 |
| 26 | 27 | 28 | 29 | 30 | 31 | NULL |
+------+------+------+------+------+------+------+
5 rows in set (0.00 sec)
这样看起来稍微有点复杂，我们拆解开来
1.构造一个1-40的临时表
with RECURSIVE c(n) as
(select 1 union all select n + 1 from c where n < 40)
2. 求出本月的第一天
SELECT adddate(current_date,-dayofmonth(current_date)+1) fd
3.通过1、2 两个步骤 构造出本月的月初到月底的每一天
SELECT adddate(fd,c.n -1) yd,
dayofweek(adddate(fd,c.n -1)) wk,
month(adddate(fd,c.n -1)) mth,
weekofyear(adddate(fd,c.n -1)) yk
from c,firstday
where month(adddate(fd,c.n -1)) = month(fd)
4.通过 weekofyear进行分组即可
SELECT max(case when wk = 2 then DATE_FORMAT(yd,’%d’) else null end) Mo,
max(case when wk = 3 then DATE_FORMAT(yd,’%d’) else null end) Tu,
max(case when wk = 4 then DATE_FORMAT(yd,’%d’) else null end) We,
max(case when wk = 5 then DATE_FORMAT(yd,’%d’) else null end) Th,
max(case when wk = 6 then DATE_FORMAT(yd,’%d’) else null end) Fr,
max(case when wk = 7 then DATE_FORMAT(yd,’%d’) else null end) Sa,
max(case when wk = 1 then DATE_FORMAT(yd,’%d’) else null end) Su
from y
group by yk
分解步骤测试记录
mysql> with recursive c(n) as
-> (
-> select 1
-> union ALL
-> select n + 1
-> from c
-> where n < 40
-> )
-> select * from c;
+------+
| n |
+------+
| 1 |
| 2 |
| 3 |
| 4 |
| 5 |
| 6 |
| 7 |
| 8 |
| 9 |
| 10 |
| 11 |
| 12 |
| 13 |
| 14 |
| 15 |
| 16 |
| 17 |
| 18 |
| 19 |
| 20 |
| 21 |
| 22 |
| 23 |
| 24 |
| 25 |
| 26 |
| 27 |
| 28 |
| 29 |
| 30 |
| 31 |
| 32 |
| 33 |
| 34 |
| 35 |
| 36 |
| 37 |
| 38 |
| 39 |
| 40 |
+------+
40 rows in set (0.00 sec)
mysql> SELECT adddate(current_date,-dayofmonth(current_date)+1) fd
-> ;
+------------+
| fd |
+------------+
| 2020-10-01 |
+------------+
1 row in set (0.00 sec)
mysql> with RECURSIVE c(n) as
-> -- 构造一个1-40的临时表
-> (select 1 union all select n + 1 from c where n < 40),
-> -- 求出本月的第一天
-> firstday AS
-> ( SELECT adddate(current_date,-dayofmonth(current_date)+1) fd),
-> -- 求出本月的每个日期及星期数
-> y AS
-> (
-> SELECT adddate(fd,c.n -1) yd,
-> dayofweek(adddate(fd,c.n -1)) wk,
-> month(adddate(fd,c.n -1)) mth,
-> weekofyear(adddate(fd,c.n -1)) yk
-> from c,firstday
-> where month(adddate(fd,c.n -1)) = month(fd)
-> )
-> select * from y;
+------------+------+------+------+
| yd | wk | mth | yk |
+------------+------+------+------+
| 2020-10-01 | 5 | 10 | 40 |
| 2020-10-02 | 6 | 10 | 40 |
| 2020-10-03 | 7 | 10 | 40 |
| 2020-10-04 | 1 | 10 | 40 |
| 2020-10-05 | 2 | 10 | 41 |
| 2020-10-06 | 3 | 10 | 41 |
| 2020-10-07 | 4 | 10 | 41 |
| 2020-10-08 | 5 | 10 | 41 |
| 2020-10-09 | 6 | 10 | 41 |
| 2020-10-10 | 7 | 10 | 41 |
| 2020-10-11 | 1 | 10 | 41 |
| 2020-10-12 | 2 | 10 | 42 |
| 2020-10-13 | 3 | 10 | 42 |
| 2020-10-14 | 4 | 10 | 42 |
| 2020-10-15 | 5 | 10 | 42 |
| 2020-10-16 | 6 | 10 | 42 |
| 2020-10-17 | 7 | 10 | 42 |
| 2020-10-18 | 1 | 10 | 42 |
| 2020-10-19 | 2 | 10 | 43 |
| 2020-10-20 | 3 | 10 | 43 |
| 2020-10-21 | 4 | 10 | 43 |
| 2020-10-22 | 5 | 10 | 43 |
| 2020-10-23 | 6 | 10 | 43 |
| 2020-10-24 | 7 | 10 | 43 |
| 2020-10-25 | 1 | 10 | 43 |
| 2020-10-26 | 2 | 10 | 44 |
| 2020-10-27 | 3 | 10 | 44 |
| 2020-10-28 | 4 | 10 | 44 |
| 2020-10-29 | 5 | 10 | 44 |
| 2020-10-30 | 6 | 10 | 44 |
| 2020-10-31 | 7 | 10 | 44 |
+------------+------+------+------+
31 rows in set (0.00 sec)
mysql> with RECURSIVE c(n) as
-> -- 构造一个1-40的临时表
-> (select 1 union all select n + 1 from c where n < 40),
-> -- 求出本月的第一天
-> firstday AS
-> ( SELECT adddate(current_date,-dayofmonth(current_date)+1) fd),
-> -- 求出本月的每个日期及星期数
-> y AS
-> (
-> SELECT adddate(fd,c.n -1) yd,
-> dayofweek(adddate(fd,c.n -1)) wk,
-> month(adddate(fd,c.n -1)) mth,
-> weekofyear(adddate(fd,c.n -1)) yk
-> from c,firstday
-> where month(adddate(fd,c.n -1)) = month(fd)
-> )
-> SELECT max(case when wk = 2 then DATE_FORMAT(yd,'%d') else null end) Mo,
-> max(case when wk = 3 then DATE_FORMAT(yd,'%d') else null end) Tu,
-> max(case when wk = 4 then DATE_FORMAT(yd,'%d') else null end) We,
-> max(case when wk = 5 then DATE_FORMAT(yd,'%d') else null end) Th,
-> max(case when wk = 6 then DATE_FORMAT(yd,'%d') else null end) Fr,
-> max(case when wk = 7 then DATE_FORMAT(yd,'%d') else null end) Sa,
-> max(case when wk = 1 then DATE_FORMAT(yd,'%d') else null end) Su
-> from y
-> group by yk;
+------+------+------+------+------+------+------+
| Mo | Tu | We | Th | Fr | Sa | Su |
+------+------+------+------+------+------+------+
| NULL | NULL | NULL | 01 | 02 | 03 | 04 |
| 05 | 06 | 07 | 08 | 09 | 10 | 11 |
| 12 | 13 | 14 | 15 | 16 | 17 | 18 |
| 19 | 20 | 21 | 22 | 23 | 24 | 25 |
| 26 | 27 | 28 | 29 | 30 | 31 | NULL |
+------+------+------+------+------+------+------+
5 rows in set (0.00 sec)
2.2 MySQL8.0之前写法
按照MySQL创建连续数字中的存储过程的方法来创建一个表t包含 1-50
MySQL生成连续数字
具体的解决方案同2.1，区别在于 构造连续数字、日期函数、封装临时表
select max(case dw when 2 then dm end) as Mo,
max(case dw when 3 then dm end) as Tu,
max(case dw when 4 then dm end) as We,
max(case dw when 5 then dm end) as Th,
max(case dw when 6 then dm end) as Fr,
max(case dw when 7 then dm end) as Sa,
max(case dw when 1 then dm end) as Su
from (
select date_format(dy,'%u') wk,
date_format(dy,'%d') dm,
date_format(dy,'%w') + 1 dw
from (
select adddate(x.dy,t.id -1) dy,
x.mth
from (
select adddate(current_date,-dayofmonth(current_date)+1) dy,
date_format(
adddate(current_date,
-dayofmonth(current_date)+1),
'%m') mth
) x,
t
where t.id <= 31
and date_format(adddate(x.dy,t.id -1),'%m') = x.mth
) y
) z
group by wk
order by wk
测试记录:
mysql> select max(case dw when 2 then dm end) as Mo,
-> max(case dw when 3 then dm end) as Tu,
-> max(case dw when 4 then dm end) as We,
-> max(case dw when 5 then dm end) as Th,
-> max(case dw when 6 then dm end) as Fr,
-> max(case dw when 7 then dm end) as Sa,
-> max(case dw when 1 then dm end) as Su
-> from (
-> select date_format(dy,'%u') wk,
-> date_format(dy,'%d') dm,
-> date_format(dy,'%w') + 1 dw
-> from (
-> select adddate(x.dy,t.id -1) dy,
-> x.mth
-> from (
-> select adddate(current_date,-dayofmonth(current_date)+1) dy,
-> date_format(
-> adddate(current_date,
-> -dayofmonth(current_date)+1),
-> '%m') mth
-> ) x,
-> t
-> where t.id <= 31
-> and date_format(adddate(x.dy,t.id -1),'%m') = x.mth
-> ) y
-> ) z
-> group by wk
-> order by wk;
+------+------+------+------+------+------+------+
| Mo | Tu | We | Th | Fr | Sa | Su |
+------+------+------+------+------+------+------+
| NULL | NULL | NULL | 01 | 02 | 03 | 04 |
| 05 | 06 | 07 | 08 | 09 | 10 | 11 |
| 12 | 13 | 14 | 15 | 16 | 17 | 18 |
| 19 | 20 | 21 | 22 | 23 | 24 | 25 |
| 26 | 27 | 28 | 29 | 30 | 31 | NULL |
+------+------+------+------+------+------+------+
5 rows in set (0.00 sec)