I have a table with a foreign key constraint and the command below gives me an error because it's trying to set a value that already in the provider table. How do I update this command to ignore those rows that already exist in the provider table?

UPDATE b SET b.iProvider_PVN = a.POIN FROM dbo.ASPVNTOPOIN_stg a INNER JOIN dbo.Provider b ON a.ASPVN = b.iProvider_PVN AND b.vcProv_Type = 'IPA' LEFT JOIN dbo.Provider c ON a.POIN = c.iProvider_PVN WHERE c.iProvider_PVN IS NULL