Find relationship between any table A and B in Sql Server

Suppose we have the following tables, with pretty foreign keys in place.

    Id int not null
    --other stuff
    Id int not null,
    PersonId int not null,
    UserId int null
    --other stuff

    Id int not null,
    Name varchar(25) not null,
    Password varchar(25) not null
    --other stuff

    Id int not null
    --other stuff

    UserId int not null,
    RoleId int not null
    --other stuff

What are the ways(query, additional software?) to ask "What is the relationship between table X and Y?"

E.g. I would like to 'ask' :

What is the relationship between tables Person and Roles?

Expected answer :

Person 1:N Employee 1:1 User 1:N UserRoles N:1 Roles

Note that tables Person and Roles do not have a direct relationship. The expected result should list the tables in-between of these two.

Something like this. A diagram representation would do, but it should only have the tables involved in the relationship.

Why I can't use "Database Diagrams" in SSMS.

Creating a relevant diagram with only needed tables takes too much time looking up the references by hand. I can't use "Add Related tables" because it makes the diagram absolutely unreadable by adding 200+ tables.

The difference from diagramming would be that I only want to input two table names.


I believe this might be what you are looking for:

select as TableWithForeignKey, as ForeignKeyColumn, as DependentOnTable, as ReferencedColumn,
from    sys.foreign_key_columns as fk
inner join sys.tables as t
on      fk.parent_object_id = t.object_id
inner join sys.columns as c
on      fk.parent_object_id = c.object_id
        and fk.parent_column_id = c.column_id
inner join sys.columns as c2
on      c2.object_id = fk.referenced_object_id
        and c2.column_id = fk.referenced_column_id
inner join sys.tables as t2
on      t2.object_id = c2.object_id
order by TableWithForeignKey

Note that all relationships in SQL server are 1:N because

neither a 1:1 can be established: How do I create a real one-to-one relationship in SQL Server

nor a N:N relationship can be established: Foreign Key to non-primary key

If you want to setup such relationships then you can merely use the extended properties to write it down for yourself and then "manually" enforce it.

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