这段linq语句是什么意思

有4个模型
Organization_Master (...org_id...)
Company_Master(...Org_ID,Name1....)
Office_Master(...Org_ID,Name1....)
Department_Master(...Org_ID,Name1....)
-------------------------------------------
public string FindOrgName(int org_id)
{
string org_name = "";
var org_m =
from o in db.db.Organization_Master
where o.Org_ID == org_id
select new
{
Name1 = (
o.Org_type == 1 ? db.Company_Master.SingleOrDefault(cm => cm.Org_ID == org_id).Name1 :
o.Org_type == 2 ? db.Office_Master.SingleOrDefault(om => om.Org_ID == org_id).Name1 :
o.Org_type == 3 ? db.Department_Master.SingleOrDefault(dm => dm.Org_ID == org_id).Name1 :
""
)
};