Migrate sqlite database to Postgres database

[José Manuel Pérez Morales]

I need to migrate from a Sqlite database to a posgrest database. But when I do it, I get the following error, which I didn't do when I was running with sqlite 
<class 'psycopg2.ProgrammingError'> column "ent.id" must appear in the GROUP BY clause or be used in an aggregate function LINE 1: ... d_on "," prov "." Created_by "," prov "." Modified_by "," ent "." Id "... ^

This error was produced by following consult to the dabtabase 

prov=db(db.ent.prov==db.prov.id).select(groupby=db.prov.id)

please some body help me