Return weekday from a stored int value with sql

[VolkerBarth]

CREATE TABLE WeekDay (DeliveryWeekdays INTEGER NOT NULL);

INSERT INTO WeekDay(DeliveryWeekdays) values (7);

We have a program that stores an int value in a table with which weekdays you have selected in a check box.

{
    None = 0,
    Monday = 1,
    Tuesday = 2,
    Wednesday = 4,
    Thursday = 8,
    Friday = 16,
    Saturday = 32,
    Sunday = 64,
}

Ex: If you have checked Monday and Thursday the value is 9 in the field in the table. If you checked Monday, Tuesday, Wednesday the value is 7 in the field and so on..

The question is whether with a date I can check if the day of the week in that date is in the int value stored in the table.

If I check the date 2020-10-08, I see that it is a Thursday. I want to check if Thursday is in value 7. The answer is yes. If the int value is 3, the answer will be no.

[VolkerBarth]

I'm not sure I understand your requirements (and is the second/third last statements true?) - but when you want to compare a value against set bits in an integer, SQL Anywhere offers bitwise operators here, see Bitwise operators. So to check against the "Thursday" flag, you could test with <myvalue> & 0x0008 != 0, and for "Friday" with <myvalue> & 0x0010 != 0.

[Former Member]

You are right, the answer in both my examples is false. I wrote wrong there. Ok, this is probably what I'm looking for. How do I write this in a sql in a condition?

[VolkerBarth]

It's difficult to show some code if we don't know how you access the test date (the possible delivery date, I assume) and the according "possible delivery week days" (per customer, I further assume). So it would be helpful to show some sample table entries...

[Former Member]

Yes, that's right. I thought of overall examples of how I can use this in practice. How, based on a date, can I convert Friday (5) to 0x0010 etc.

[fvestjens]

Is this what you're looking for:

select dow(current date) weekday, POWER(2,weekday-2) theday, (if (theday & 0x12) = 0 then 1 else 0 endif)