How could I check if those records exists in SQL ?

Question

I have a list which is holidng several properties like date time , url, id and so on 

before i import this list into DB i want to check if those records are already existing in DB  

// here is the list
GetListofProducts = GetAllProdcuts();
// after that i am importing the list into a DB

ImportIntoDB();

// but before that i want to check if the records in this list are already exist in DB