Split function in where clause

Question

hello friends

I am using following query in linq

In product table following type of data are stored

abc-def bcd=fgh abc-xyz

var query=from prod in db.Product join cat in db.category on prod.categoryId=cat.categoryID where prod.productName.split('-')[0]=="abc"

but in that query it product annoumous problem

Please give some suggestion to split in where caluse