Relationship with join and select

Databases
1

Hello

I am very confused and frustrated here. What relationship does the columns in SELECT have with the actual JOIN query.

Ive got these three tables in my SELECT
dbUsers., dbPosts., dbKarma.*

but when I add a fourth table
dbUsers., dbPosts., dbKarma., dbPosts_share.

the whole query stops outputting results.

What relationship does the SELECT have with the JOIN query?
Why would this effect the query?
As far as I know, SELECT is for the actual output in the loop?

2

most likely because of either (1) a syntax error, or (2) an implicit cross join which returns a bazillion rows, and the query never finishes executing

it determines which column(s) are to be returned from the join

it wouldn’t

there is no such thing as a loop in mysql, but i think you have the right idea, the SELECT determines which columns are to be returned

3

Hi.

What would happen if I added a table that is not in the join?
Is it expected to work?

4

I just did an SQL query in PhpMyAdmin with an additional table in the SELECT which is in my join query but I get an error saying “unknown table” why is this happening?

5

Can you post the structure of the tables concerned and the query that you’ve got so far?

6

without seeing the query, and without knowing which tables you actually have, i would only be guessing

if you want help, you have to give us more to go on…