I am trying to make an SQL query from a data extension with a data view, but i can't get it to work.
SELECT a.id as Id , a.email as email , a.FirstName as FirstName from contact_salesforce a left join _Open o on o.SubscriberKey = a.id
it gives an error when i do the automation:
"Query failed during execution. Error: Violation of PRIMARY KEY constraint. Cannot insert duplicate key in object"
Data Extension fields:
Id Text 18
Email EmailAddress 254
FirstName Text 40