SQL join on N-M realtion with AND condition - sql

Question

I have TableA and TableB and a relation TableAB for a many to many (N-M) relation
TableA JOIN TableAB JOIN TableB
How can I add an AND-condition to check if TableAB has entries for multiple conditions in TableB
Maybe a stupid but simple example:
TableA = firstnames
TableB = lastnames
I want all firstnames that are used in combination with lastname "Smith", "Black" AND "Taylor"
I thought about using
WHERE lastname = "Smith" or lastname = "Black" or lastname = "Taylor"
GROUP BY firstname and check if count(*) = 3
But this seems to be not the right way, as lastname = "Smith" or lastname = "Smith" or lastname = "Smith" should not return an empty table.
And it should be easy to extend, as the filter is user input, and don't know how many conditions I get.
Bonus question: I use Sequelize with a Many-to-Many Association, not sure how to put this in here
EDIT:
Example:
TableA
id
firstname
1
Tom
2
Alice
3
Bob
TableB
id
lastname
1
Smith
2
Black
3
Taylor
TableAB
id
id_firstname
id_lastname
1
1
1
2
2
1
3
2
2
2
3
3
Meaning we have Tom Smith, Alice Smith, Alice Black, Bob Taylor
Query: Give me all firstnames with lastname Smith AND Black
Result: Alice

Answer 1

as always: there are different ways to achieve that. One is a multiple join of the NM table. Check the select on the end of the script (written for MS SQL Server). The rest of the script is just to create the sample data.
create table TableA (
ID int not null,
Firstname nvarchar(255) not null);
create table TableB (
ID int not null,
Lastname nvarchar(255) not null);
create table TableAB(
IDA int not null,
IDB int not null);
GO
insert into TableA values (1, 'Tom');
insert into TableA values (2, 'Alice');
insert into TableA values (3, 'Bob');
insert into TableB values (1, 'Smith');
insert into TableB values (2, 'Black');
insert into TableB values (3, 'Taylor');
insert into TableAB values (1, 1);
insert into TableAB values (2, 1);
insert into TableAB values (2, 2);
insert into TableAB values (3, 3);
GO
select A.Firstname
from TableA A
inner join TableAB AB1 on A.ID = AB1.IDA
inner join TableB B1 on B1.ID = AB1.IDB
inner join TableAB AB2 on A.ID = AB2.IDA
inner join TableB B2 on B2.ID = AB2.IDB
where B1.Lastname = 'Smith'
and B2.Lastname = 'Black'
other way would be a sub-select to return all combinations of Lastname + Firstname and then filter for the requested Lastname and count the occurance:
select Firstname
from (
select distinct A.Firstname, B.Lastname
from TableA A
inner join TableAB AB on A.ID = AB.IDA
inner join TableB B on B.ID = AB.IDB
) t
where Lastname in ('Smith', 'Black')
group by Firstname
having count(*) = 2
Both ways will return Alice as a result only.

Answer 2

Thank you for your reply. The second one is similar to what I thought would work:
select A.Firstname, B.Lastname
from TableA A
inner join TableAB AB on A.ID = AB.IDA
inner join TableB B on B.ID = AB.IDB AND Lastname in ('Smith', 'Black')
group by A.Firstname having count(*) = 2
But it must be checked if all user inputs of lastnames are distinct as "in ('Smith', 'Smith')" will not work with count = 2
That's why I thought there exists better solutions. The first suggestion would be fine with this, but its a mess to implement this automated with prepared statements in sequelize.