How to join these queries? So I currently have this query:

SELECT v.Voorstellingsnummer, COUNT(r.Voorstellingsnummer) 
FROM reserveringen r, voorstelling v 
WHERE r.Voorstellingsnummer = v.Voorstellingsnummer 
GROUP BY r.Voorstellingsnummer HAVING COUNT(*) &lt; 50


That query outputs this table:

Voorstellingsnummer  COUNT(r.Voorstellingsnummber)
-------------------  -----------------------------
4                    1
5                    2


The other query is this one:

SELECT v.Tijd, v.Voorstellingsnummer
FROM voorstelling v
WHERE v.Vestigingsnaam = 'Amsterdam' 
AND v.Filmnaam = 'Avengers' 


...which outputs this:

Tijd                 Voorstellingsnummer
-------------------  -------------------
2019-03-24 11:12:00  5
2019-03-24 15:12:00  4


Considerations


I need to add a COUNT(v.Voorstellingsnummer) column to the last image the same way as it is in the first one.
And then I need to add those COUNTS together to give a totalcount.
That total count should be lower than a set number and if it's higher it should not be shown.


When I do this:

SELECT v.Tijd, v.Voorstellingsnummer, COUNT(v.Voorstellingsnummer)
FROM voorstelling v
WHERE v.Vestigingsnaam = 'Amsterdam' 
AND v.Filmnaam = 'Avengers' 


...it returns this:

Tijd,                Voorstellingsnummer, COUNT(v.Voorstellingsnummer)
2019-03-24 11:12:00, 5,                   2


...but instead it should show both the times form the second picture both with a count of 1.

Those counts of 1 should be combined with the other table so the final counts of 
Voorstellingsnummer=4 should be 2
and Voorstellingsnummer=5 should be 3

Can anyone tell me how to do this?

Further information

Basically if the table reserveringen look has (Voorstellingsnummer = 4) 6x 
and the table voorstelling has (Voorstellingsnummer = 4) 2x
the count outputted by the query should be 8x.

However, currently if (Voorstellingsnummer = 4) appears 3x in the table voorstelling, but has 0 appearances in the table reserveringen it won't be counted.

So what I'm thinking is running this query:

SELECT v.Voorstellingsnummer, COUNT(r.Voorstellingsnummer) 
FROM reserveringen r, voorstelling v 
WHERE r.Voorstellingsnummer = v.Voorstellingsnummer 
GROUP BY r.Voorstellingsnummer HAVING COUNT(*) &lt; 50


for the table reserveringen and the table voorstelling. That should result in two tables. The result of the query for table voorstelling should look like this (using number previously mentioned):

Tijd         Voorstellingsnummer   COUN
----------   -------------------   ----
something    5                      1
something    4                      1


..and then the result for the query for table reserveringen should look as follows:

Voorstellingsnummer   COUNT
-------------------   -----
5                      2


That's because table reserveringen has no Tijd column.

Those two tables should then be combined into the following one:

Tijd         Voorstellingsnummer    COUNT
---------    -------------------    -----
something    5                      3
something    4                      1


Basically both Voorstellingsnummer 4/5 approve of the condition Vestigingsnaam='Amsterdam' AND Filmnaam='Avengers'; however only Voorstellingsnummer 5 appears in the reserveringen table. Because of that I need to know how much appearances Voorstellingsnummer = (Some number) has over both tables.

Note: Reserveringen means reservations in dutch, and voorstelling is show. 
Some shows might have reservations but some might not. Because the show without reservations should still be listed (as it's not full yet).
In advance i've never written anything in mysql, but the theory should still be there in case of small syntax errors.

In general i'd advice using INNER JOINS, instead of joining your tables in a WHERE clause, due to easier readability and better coding practice, as it makes it easy to change the sql inner join to an outer join as i've shown below:

SELECT v.Voorstellingsnummer, COUNT(r.Voorstellingsnummer)+1 
FROM voorstelling v
INNER JOIN reserveringen r ON r.Voorstellingsnummer = v.Voorstellingsnummer
WHERE v.Vestigingsnaam = 'Amsterdam' 
AND v.Filmnaam = 'Avengers' 
GROUP BY r.Voorstellingsnummer HAVING COUNT(*) &lt; 50


I am however very confused as to how you want the counts added? The above query should return what you're asking for. As it sounds like you just want the initial counts to be added with 1. To have this match more function like instead of a hardcoded value, i would have to understand why 4 and 5 should have a count of 1 in the other table?