Get number of monday in a rangedate mysql - mysql

Question

Get number of monday in a rangedate MySQL, I run this code but it give me result 0:
select count(*) from tarif where weekday(`end_tarif`<= '2019-02-21'AND `start_tarif`>='2019-02-05') = 0;
my table:
CREATE TABLE `tarif` (
`tarif_id` int(11) NOT NULL AUTO_INCREMENT,
`start_tarif` date NOT NULL,
`end_tarif` date NOT NULL,
`day_tarif` varchar(50) NOT NULL,
PRIMARY KEY (`tarif_id`)
);
INSERT INTO `tarif` VALUES (1, '2019-02-01', '2019-02-10', '10'),
(2, '2019-02-11', '2019-02-20', '20'),
(3, '2019-02-21', '2019-02-28', '10'),
(4, '2019-03-01', '2019-02-10', '15');

Answer 1

You can use a solution using a calendar table. So you can use a solution like the following:
1. create a table with calendar data
-- create the table "calendar"
CREATE TABLE `calendar` (
`dateValue` DATE
);
-- insert the days to the table "calendar"
INSERT INTO calendar
SELECT adddate('1970-01-01',t4*10000 + t3*1000 + t2*100 + t1*10 + t0) gen_date from
(select 0 t0 union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t0,
(select 0 t1 union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t1,
(select 0 t2 union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t2,
(select 0 t3 union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t3,
(select 0 t4 union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t4
HAVING gen_date BETWEEN '2019-01-01' AND '2019-12-31'
You can find the script to generate the calendar data on StackOverflow:
How to populate a table with a range of dates?
2. create the table with your data (with monday tarif)
-- create the table "tarif"
CREATE TABLE tarif (
tarif_id INT(11) NOT NULL AUTO_INCREMENT,
start_tarif DATE NOT NULL,
end_tarif DATE NOT NULL,
day_tarif VARCHAR(50) NOT NULL,
monday_tarif VARCHAR(50) NOT NULL,
PRIMARY KEY (tarif_id)
);
-- insert the tarif information
INSERT INTO tarif VALUES
(1, '2019-02-01', '2019-02-10', '10', '5'),
(2, '2019-02-11', '2019-02-20', '20', '5'),
(3, '2019-02-21', '2019-02-28', '10', '5'),
(4, '2019-03-01', '2019-02-10', '15', '5');
Note: To create a useful example I added the column monday_tarif and insert the value 5 on every date range.
3. get the result
Now you can get all days of your needed range (between 2019-02-05 and 2019-02-21) from the calendar table. With a LEFT JOIN you add your tarif table to all days of date range.
With a CASE WHEN and the condition DAYOFWEEK = 2 or DAYNAME = 'Monday' you can check if the current date is a Monday or not, to get the correct tarif value of the day.
SELECT SUM(CASE WHEN DAYOFWEEK(cal.dateValue) = 2 THEN tarif.monday_tarif ELSE tarif.day_tarif END) AS sumWithMondayTarif
FROM calendar cal
LEFT JOIN tarif ON cal.dateValue BETWEEN start_tarif AND end_tarif
WHERE cal.dateValue BETWEEN '2019-02-05' AND '2019-02-21';
You can also use a SELECT with a sub select of the calendar:
SELECT SUM(CASE WHEN DAYOFWEEK(cal.dateValue) = 2 THEN tarif.monday_tarif ELSE tarif.day_tarif END) AS sumWithMondayTarif FROM (
SELECT adddate('1970-01-01',t4*10000 + t3*1000 + t2*100 + t1*10 + t0) dateValue FROM
(select 0 t0 union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t0,
(select 0 t1 union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t1,
(select 0 t2 union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t2,
(select 0 t3 union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t3,
(select 0 t4 union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t4
HAVING dateValue BETWEEN '2019-02-05' AND '2019-02-21'
) cal LEFT JOIN tarif ON cal.dateValue BETWEEN start_tarif AND end_tarif
demo on dbfiddle.uk

Answer 2

Below mentioned query is for sundays count. you can modify it as per your requirement
select ROUND((
(unix_timestamp(`end_tarif`) - unix_timestamp(`start_tarif`) )/(24*60*60)
-7+WEEKDAY(`start_tarif`)-WEEKDAY(`end_tarif`)
)/7)
+ if(WEEKDAY(`start_tarif`) <= 6, 1, 0)
+ if(WEEKDAY(`end_tarif`) >= 6, 1, 0) as Sunday
from tarif
where `end_tarif`<= '2019-02-21' AND `start_tarif`>='2019-02-05' ;