How can I write the query in SQL of only certain combinations in a table?

I have a table where the days that certain clients must be visited are recorded (Monday, Tuesday, Wednesday, Thursday and Friday), I attach this to illustrate:

I must create a query that only extracts the clients that are visited only on the days (Monday, Wednesday and Friday), or combinations such as: Monday-Wednesday, Monday-Friday, Wednesday-Friday, Monday-Wednesday-Friday, only Monday, only Wednesday, only Friday. I looking forward the output like this image

How can I write this in SQL?

Assuming your data appears exactly as described then you just need to filter out individual rows. You're not interested in combinations per se you just want only clients that have all of their visitation contained within the three days Monday, Wednesday, and Friday. Flipping that around then you want to disqualify based on the other four days. The most concise way to write that is this:

select * from T
where 'x' not in (Tuesday, Thursday, Saturday, Sunday);

I'm assuming that none of these flags are represented are nulls. If that's the case then just expand to a longer form:

where   coalesce(Tuesday, '')  <> 'x'
    and coalesce(Thursday, '') <> 'x'
    and coalesce(Saturday, '') <> 'x'
    and coalesce(Sunday, '')   <> 'x';

or equivalently and more to the point:

where Tuesday is null and Thursday is null and Saturday is null and Sunday is null;

This can be translated to : select clients who are not visited Tuesday,Thursday, Saturday or Sunday.

You can use group by and having clause to achieve this :

select client
from mytable
group by client
having sum(case when Tuesday = 'x' then 1 else 0 end ) = 0
       and sum(case when Thursday = 'x' then 1 else 0 end ) = 0
       and sum(case when Saturday = 'x' then 1 else 0 end ) = 0
       and sum(case when Sunday = 'x' then 1 else 0 end ) = 0

If there is only one row per client then you can simply do it as follows :

select *
from mytable
where Tuesday = ''
       and Thursday = '' 
       and Saturday = '' 
       and Sunday = ''

Demo on sql server

I solve the problemn with this query:

SELECT Client.Number,
CASE 
WHEN Cliente.MONDAY = 'X' 
THEN (CASE WHEN Cliente.TUESDAY = 'X' OR Cliente.THURSDAY = 'X' OR 
Cliente.SATURDAY = 'X' OR Cliente.SUNDAY = 'X' THEN 0
		ELSE 1 END)
WHEN Cliente.WEDNESDAY = 'X'  
THEN (CASE WHEN Cliente.TUESDAY = 'X' OR Cliente.THURSDAY = 'X' OR 
Cliente.SATURDAY = 'X' OR S2.SUNDAY = 'X' THEN 0
		ELSE 1 END)
WHEN Cliente.FRIDAY = 'X'  
THEN (CASE WHEN Cliente.TUESDAY = 'X' OR Cliente.THURSDAY = 'X' OR 
Cliente.SATURDAY = 'X' OR Cliente.SUNDAY = 'X' THEN 0
		ELSE 1 END)
ELSE 0
END Resultado
from TableClients Client

Because also to me I am interesting about combinations in where not appear the others days.

i add parameters as table, so you can make any combination base on table rows in @d table. (you can put in stored proc with input parameter as user table variable)

declare @t table (
  client varchar(20),
  Monday bit, 
  Tuesday bit, 
  Wednesday bit,  
  Thursday bit, 
  Friday bit, 
  Saturday bit, 
  Sunday bit
)

insert into @t values
('client 1', 1, 0, 0, 0, 0, 0, 0),
('client 2', 0, 0, 1, 0, 0, 0, 1),
('client 3', 1, 0, 1, 0, 1, 0, 0),
('client 4', 1, 0, 1, 0, 0, 0, 0),
('client 5', 0, 1, 1, 1, 1, 0, 0),
('client 6', 0, 1, 1, 1, 1, 0, 0);

declare @d table (Days varchar(20))
insert into @d values ('Monday'), ('Sunday')


select * 
from @t t
where 
	t.Monday = case when exists (select top 1 Days from @d where days = 'Monday') then 1 else null end
or t.Tuesday = case when exists (select top 1 Days from @d where days = 'Tuesday') then 1 else null end  
or t.Wednesday = case when exists (select top 1 Days from @d where days = 'Wednesday') then 1 else null end  
or t.Thursday = case when exists (select top 1 Days from @d where days = 'Thursday') then 1 else null end
or t.Friday = case when exists (select top 1 Days from @d where days = 'Friday') then 1 else null end
or t.Saturday = case when exists (select top 1 Days from @d where days = 'Saturday') then 1 else null end
or t.Sunday = case when exists (select top 1 Days from @d where days = 'Sunday') then 1 else null end

in example i choose Monday and Sunday
result would be