Customization connect to Db. to get access to all tables for LINQ query

[maverick (Nancy)]

I am in a customization (not a BPM) and want to connect to the Db. and get all tables; like:

Db.JobAsmbl
Db.Part

What do I need to call in order to execute a query like this in form customization?
string jobnum = “123”;
var query = (from JobAsmbl in Db.JobAsmbl
join Parts in Db.Part
on new { JobAsmbl.Company, JobAsmbl.PartNum }
equals new { Part.Company, Part.PartNum }
where
JobAsmbl.JobNum == jobnum &&
Part.ProdCode == “CONF”
select new
{
JobAsmbl.Company,
JobAsmbl.JobNum,
JobAsmbl.AssemblySeq,
JobAsmbl.PartNum,
Part.ProdCode
}));