Query below lists tables with most relationships (both foreign keys and FK references from other tables).

See also:

• Tables with most foreign keys ,
• Summary article of FK queries for SQL Server.

Query

select tab as [table],
    count(distinct rel_name) as relationships,
    count(distinct fk_name) as foreign_keys,
    count(distinct ref_name) as [references],
    count(distinct rel_object_id) as related_tables,
    count(distinct referenced_object_id) as referenced_tables,
    count(distinct parent_object_id) as referencing_tables
from 
    (select schema_name(tab.schema_id) + '.' + tab.name as tab,
        fk.name as rel_name,
        fk.referenced_object_id as rel_object_id,
        fk.name as fk_name,
        fk.referenced_object_id,
        null as ref_name,
        null as parent_object_id
    from sys.tables as tab
        left join sys.foreign_keys as fk
            on tab.object_id = fk.parent_object_id
    union all
    select schema_name(tab.schema_id) + '.' + tab.name as tab,
        fk.name as rel_name,
        fk.parent_object_id as rel_object_id,
        null as fk_name,
        null as referenced_object_id,
        fk.name as ref_name,
        fk.parent_object_id
    from sys.tables as tab
        left join sys.foreign_keys as fk
            on tab.object_id = fk.referenced_object_id) q
group by tab
order by count(distinct rel_name) desc

Columns

• table - name of table with schema name
• relationships - number of relationships (FKs and FK references)
• foreign_keys - number of foreign keys in a table
• references - number of FK references from other tables
• related_tables - number of different related tables (regardless of relationship type/direction table is counted only once)
• referenced_tables - number of different tables referenced with FKs (please note that table can be related more than once so number of FKs and number of referenced tables can be different)
• referencing_tables - number of different tables referencing with foreign keys this table

Rows

• One row represents one table in a database
• Scope of rows: all tables in a database
• Ordered by number of relationships (foreing keys and references) from the ones with the most

Sample results