sorry, not enough reputation to post images. I have 3 SQL tables:
x1: {‘a’:1,2,3,4,5},
x2: {‘c’:1,1,1,2,2,3,3, ‘d’:1,3,5,1,3,1,1},
x3: {‘b’:1,3,5}
The query is:
select a from x1
where not exists (
select * from x3
where not exists (
select *
from x2
where x1.a = x2.c and x3.b=x2.d
)
)
The result from the following query is ‘1‘, but I can’t understand what are the steps taken to get to that result.
What is being returned in which subquery?