Issues with the OR clause - tsql

Question

I am having some trouble with the OR clause.
I am trying to join two large tables and given below is a sample data from the tables
Table1 (t1)
vendor addr1 city zip
ADT PO BOX 371956 PITSBURGH 15250
Table2 (t2)
vendor addr1 city zip
ADT PO Box 371956 Pittsburgh 15250-7956
The first two select statements given below display one row of data from the two tables.
In the third select, I have an OR clause and this does not display any rows.
The OR clause should not affect the result set.
select *
from t1
left join t2
on t1.addr1 = t2.addr1
select *
from t1
left join t2
on t1.addr1 = t2.addr1
and (t1.city = t2.city)
the select below does not display any data. WHY?
select *
from t1
left join t2
on t1.addr1 = t2.addr1
and ((t1.city = t2.city) or (t1.zip = t2.zip))

Answer 1

On your last query you have:
t1.addr1 = t2.addr2 AND
(
t1.city = t2.city OR
t1.zip = t2.zip
)
Considering your sample data:
t1."PO BOX 371956" = t2."PO Box 371956" AND -- TRUE
(
t1."PITSBURGH" = t2."Pittsburgh" OR -- FALSE
t1."15250" = t2."15250-7956" -- FALSE
)
You got:
= TRUE AND (FALSE OR FALSE)
= TRUE AND FALSE
= FALSE
So, no soup for you.