How to query data from Salesforce Contact Object


Please help me in this condition.

When a Contact Object Record is created from Skuid Page.Suppose that Skuid page is having a field named “Email” .
I want to add a condition that while creating a new Contact record from that skuid page if the email id entered by a user already exists in any of the Contact object record,a error message get displayed like “Duplicate Email Id Not Allowed” and Record not save.