postgresql returns null but mysql doesn't - mysql

Question

I have an application for which I am migrating from Mysql to Psql.
I have three tables t1,t2,t3 described below . Table t3 will always have a entry as long as user is available , but both table t1 and t2 may or may not have entry if the user doesn't create DB in his account.
While executing q1 in mysql , I get result set containing values fetched from table t3, even if t1 and t2 doesn't have entry , but it returns null in psql . So I've written two queries pq1 and pq2 to be equivalent to q1 . What is the reason that mysql doesn't return null values but psql does? Is there any better solution to this than breaking down into two queries for psql ?
mysql query (q1)
select
COALESCE(sum(dr.NO_OF_QT),0),
ur.NO_OF_USERS, ur.NO_OF_DB, 0,
COALESCE(sum(dr.NO_OF_SM),0),
COALESCE(sum(dr.NO_OF_RPTS),0)
from DataBaseProps dr
left join DataBaseDetails db on dr.DB_ID=db.ID and db.STATUS=1
left join UserProps ur on db.OWNER_UID=ur.USER_UID
where ur.USER_UID='USER_UID'
Psql-query_1 (pq1)
select
COALESCE(sum(dr.NO_OF_QT),0),
0,0, 0,
COALESCE(sum(dr.NO_OF_SM),0),
COALESCE(sum(dr.NO_OF_RPTS),0)
from DataBaseProps dr
left join DataBaseDetails db on dr.DB_ID=db.ID and db.STATUS=1
left join UserProps ur on db.OWNER_UID=ur.USER_UID
where ur.USER_UID='USER_UID'
psql-query_2(pq2)
select NO_OF_USERS,NO_OF_DB from UserProps
where USER_UID='USER_UID'
Table 1 DataBaseProps (t1)
desc DataBaseProps >
+-----------------+------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-----------------+------------+------+-----+---------+-------+
| DB_ID | bigint(19) | NO | PRI | NULL | |
| NO_OF_RPTS | int(10) | YES | | 0 | |
| NO_OF_QT | int(10) | YES | | 0 | |
| NO_OF_SM | int(10) | YES | | 0 | |
+-----------------+------------+------+-----+---------+-------+
Table 2 - DataBaseDetails(t2)
desc DataBaseDetails>
+-------------------+--------------+------+-----+-----------------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------------------+--------------+------+-----+-----------------+-------+
| ID | bigint(19) | NO | PRI | NULL | |
| NAME | varchar(50) | NO | | NULL | |
| STATUS | int(10) | NO | | 1 | |
| OWNER_UID | bigint(19) | NO | | NULL | |
+-------------------+--------------+------+-----+-----------------+-------+
Table 3 UserProps(t3)
desc UserProps>
+-----------------+------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-----------------+------------+------+-----+---------+-------+
| USER_UID | bigint(19) | NO | PRI | NULL | |
| NO_OF_DB | int(10) | YES | | 0 | |
| NO_OF_USERS | int(10) | YES | | 0 | |
+-----------------+------------+------+-----+---------+-------+