Query below lists tables that are not referenced by the foreign keys.

See also:
Query
select '>- no FKs' as foreign_keys,
       tab.table_schema,
       tab.table_name
from information_schema.tables tab
where tab.table_type ='BASE TABLE'
      and tab.table_schema || '.' || tab.table_name not in
          (select distinct tco.table_schema || '.' ||tco.table_name
           from information_schema.referential_constraints rco
           join information_schema.table_constraints tco
                on rco.unique_constraint_name = tco.constraint_name
                and rco.unique_constraint_schema = tco.table_schema)
order by tab.table_schema,
         tab.table_name;
Columns
- foreign_keys - symbol indicating lack of FK references
- table_schema - name of the schema in which table resides
- table_name - table name
Rows
- One row represents one table
- Scope of rows: all tables not referenced by the foreign keys
- Ordered by table schema and table name
Sample results

 
                                                                     
                                                                     
                                                                     
                                                                     
                                                                     
                                                                     
                                                                     
                                                                     
                                                                     
                                                                     
                                                                     
                                                                     
                                                                     
                                                                     
                                                                     
                                                                     
                                                                     
                                                                 
                                                             
                                                             
                                                             
                                                             
                                                                 
                                                             
                                                             
                                                                 
                                                             
                                                             
                                                             
                                                             Bart Gawrych
                                                                        Bart Gawrych
                                 Snowflake
                                                                Snowflake
                                 SQL Server
                                                                                                SQL Server
                                             Azure SQL Database
                                                                                                Azure SQL Database
                                             Amazon Redshift
                                                                                                Amazon Redshift
                                             IBM Db2
                                                                                                IBM Db2
                                             Teradata
                                                                                                Teradata
                                             Vertica
                                                                                                Vertica
                                             PostgreSQL
                                                                                                PostgreSQL
                                             MySQL
                                                                                                MySQL
                                             MariaDB
                                                                                                MariaDB