Frequent-Error-Messages.md

-# ERROR: duplicate key violates unique constraint '...'
+# ERROR: duplicate key violates unique constraint 'sampling_sites_identifier_sampling_site_key'
 
 ## Cause
-You try to insert data in a table and the identifier of one or many rows already exists in the database. 
+You try to insert data in a table (here _sampling_sites_) and the identifier (here column _identifier_sampling_site_) of one or many rows already exists in the database. 
 
-Either somebody has already imported the same data set or somebody has at least used the same value in the identifier column.
+Either somebody has already imported the same data set or somebody has at least used the same value in the identifier column (here _identifier_sampling_site_).
 
 ## Solution
 Check the already existing data in the database for that table. If your data were already imported, either you are happy with them or you need to contact the user who imported the data. Who this is can be found in the column _created_by_ .