fix #1977 (#2034)

tools/goctl/model/sql/model/postgresqlmodel.go

@@ -81,6 +81,7 @@ from (
            and a.attnum > 0
            and a.attrelid = c.oid
            and a.atttypid = t.oid
+ 		 GROUP BY a.attnum, c.relname, a.attname, t.typname, a.atttypmod, a.attnotnull, b.description
          ORDER BY a.attnum) AS t
          left join information_schema.columns AS c on t.relname = c.table_name 
 		and t.field = c.column_name and c.table_schema = $2`