You need to embed the PlatformMap and Platforms tables twice
Use PM2 as the PlateformMap where PlatformID=2
Use PF2 for PlatformID check of 2
Use PM4 as the PlateformMap where PlatformID=4
Use PF4 for PlatformID check of 4
Join PM2 and PM4 where TraderIDs are equal
select distinct
select distinct
TraderPersonalInfo.TraderID,PM2.PlatformID,PM4.PlatformID
from TraderPersonalInfo,Locations,Platforms PF2,Platforms PF4,
PlatformMap PM2,PlatformMap PM4
where (TraderPersonalInfo.TraderID = PM2.TraderID)
and (PM2.PlatformID = PF2.PlatformID)
and PM2.PlatformID = 2
and
