how to set days of the week using sqlite - c++

Question

I have created table with Employee, and I have columns such as Name, WorkingDays (datatype is date). I want to write a query that will output something like
"select Name from Employee where WorkingDay = 'monday', 'wednesday' and 'friday' "
i.e..I want to make a roaster for the workers. I am using sqlite and QT. thanks in advance.

Answer 1

As per Date And Time Functions documentation, you can use strftime function in this way:
SELECT Name FROM Employee WHERE strftime('%w',WorkingDay) IN ('1','3','5');
Where ('1','3','5') are ('Monday', 'Wednesday', 'Friday') respectively.
An off-topic note:
WorkingDays (datatype is date)
There's no such thing in SQLite. From Datatypes In SQLite Version 3 documentation:
1.2 Date and Time Datatype
SQLite does not have a storage class set aside for storing dates
and/or times. Instead, the built-in Date And Time Functions of SQLite
are capable of storing dates and times as TEXT, REAL, or INTEGER
values:
TEXT as ISO8601 strings ("YYYY-MM-DD HH:MM:SS.SSS").
REAL as Julian day numbers, the number of days since noon in Greenwich on November 24, 4714 B.C. according to the proleptic
Gregorian calendar.
INTEGER as Unix Time, the number of seconds since 1970-01-01 00:00:00 UTC.
Applications can chose to store dates and times in any of these
formats and freely convert between formats using the built-in date and
time functions.
Update
so that for example if today is friday, then automatically this name
appears on the names working today. Is it possible?
Yes it is. Just need to use strftime() function properly. I'll give you a little example:
CREATE TABLE Employee(
id INTEGER PRIMARY KEY,
name VARCHAR
);
CREATE TABLE WorkingDays(
id INTEGER PRIMARY KEY,
employee INTEGER,
dayNumber INTEGER,
FOREIGN KEY(employee) REFERENCES Employee(id),
UNIQUE(employee,dayNumer)
);
INSERT INTO Employee(name) VALUES('Max');
INSERT INTO Employee(name) VALUES('dic19');
INSERT INTO WorkingDays(employee,dayNumber) VALUES(1,1); --Max, Monday
INSERT INTO WorkingDays(employee,dayNumber) VALUES(1,2); --Max, Tuesday
INSERT INTO WorkingDays(employee,dayNumber) VALUES(1,3); --Max, Wednesday
INSERT INTO WorkingDays(employee,dayNumber) VALUES(2,4); --dic19, Thursday
INSERT INTO WorkingDays(employee,dayNumber) VALUES(2,5); --dic19, Friday
INSERT INTO WorkingDays(employee,dayNumber) VALUES(2,6); --dic19, Saturday
SELECT e.name
FROM WorkingDays w
LEFT JOIN Employee e ON w.employee = e.id
WHERE cast(w.dayNumber as text) = strftime('%w','now');
-- Right now it should return 'dic19' because Today is Friday/Saturday (depends on time zone)
SELECT e.name
FROM WorkingDays w
LEFT JOIN Employee e ON w.employee = e.id
WHERE cast(w.dayNumber as text) = strftime('%w','2013-11-11');
-- Should return 'Max' because '2013-11-11' was Monday