How do you Update a Hubspot Contact with email

I need to pull data from a sql database into Hubspot. Right now the option to update a contact requires the Hubspot ID but I do not have that in the sql database, I have their email which should be able to be used as the unique identifier. How should you now go about doing this update, do you have to use the email to search for email and then update the information. I tried that and get errors so I am now lost. Do I have to revert to using Zapier?