How to join three table using inner join in postgres sql

Question

I am trying to get the data from the three table using inner join but its sows me empty result.

select comp.gps_time as complaint_register_date,comp.accept_date as complaint_accept_date,comp.name as citizen_name,comp.road_id,dept.dept_name,circle.circle_name,division.div_name 
from complaints as comp 
 INNER JOIN department as dept ON dept.dept_code=comp.dept_code 
 INNER JOIN circle as circle on circle.circle_code=comp.circle_code 
 INNER JOIN division as division on division.div_code=comp.div_code 
where comp.templateid != null

complaint table

Complaint_Id Roadid Dept_code Div_code Circle_code Name Templateid Accept_date Gps_time
162 167889 3 1 4 Xyz 3 2019年02月25日 09:40:39 2019年02月23日 09:40:39
168 167880 2 4 6 abc null 2019年02月25日 09:40:39 2019年02月23日 09:40:39

Department table

Dept_code Dept_name
3 Abcdept
2 Zyzdept
1 syzdept

Circle table

Circle_code Circle_name
4 Xcircle
6 ycircle

Division Table

Division_code Division_name
1 Ydiv
2 ndiv
4 zdiv

Answer 1

You can't test for null using = or <> (or !=)

To test for non-null values you need to use IS NOT NULL:

where comp.templateid is not null