sql - Ignore null values in select statement -

i'm trying retrieve list of components via computer_system, if computer system's graphics card set null (i.e. has onboard), row isn't returned select statement.

i've been trying use coalesce without results. i've tried , or in clause, returns computer system different kinds of graphic cards.

relevant code:

select computer_system.cs_id,  computer_system.cs_name,  motherboard.name,  motherboard.price,  cpu.name,  cpu.price,  gfx.name, gfx.price  public.computer_case ,  public.computer_system,  public.cpu,  public.gfx,  public.motherboard,  public.ram  computer_system.cs_ram = ram.ram_id , computer_system.cs_cpu = cpu.cpu_id , computer_system.cs_mb = motherboard.mb_id , computer_system.cs_case = computer_case.case_id ,  computer_system.cs_gfx = gfx.gfx_id; <-- ( or computer_system.cs_gfx null) 

returns:

1;"computer1";"fractal design"; 721.00; "msi z87"; 982.00; "core i7 i7-4770k "; 2147.00; "crucial gamer"; 1253.00; "asus gtx780";3328.00 

should use joins? there no easy way return requested row, if there's bloody null value. been struggling @ least 2 hours.

tables posted if needed.

edit: should return second row:

2;"computer2";"fractal design"; 721.00; "msi z87"; 982.00; "core i7 i7-4770k "; 2147.00; "crucial gamer"; 1253.00; "null/nothing";null/nothing 

you want left outer join.

first, clean code use ansi joins it's readable:

select     computer_system.cs_id,      computer_system.cs_name,      motherboard.name,      motherboard.price,      cpu.name,      cpu.price,      gfx.name,     gfx.price      public.computer_system     inner join public.computer_case on computer_system.cs_case = computer_case.case_id     inner join public.cpu on computer_system.cs_cpu = cpu.cpu_id     inner join public.gfx on computer_system.cs_gfx = gfx.gfx_id     inner join public.motherboard on computer_system.cs_mb = motherboard.mb_id     inner join public.ram on computer_system.cs_ram = ram.ram_id; 

then change inner join on public.gfx left outer join:

    left outer join public.gfx on computer_system.cs_gfx = gfx.gfx_id 

see postgresql tutorial - joins.

i recommend reading introductory tutorial sql - @ least postgresql tutorial, preferably more material well.