prueba esta consulta:
Tienes que usar sysreferences y objetos del sistema tablas para obtener la información
La consulta a continuación proporciona todas las claves foráneas, así como las tablas principales con los nombres de las columnas de la base de datos
select cast(f.name as varchar(255)) as foreign_key_name
, cast(c.name as varchar(255)) as foreign_table
, cast(fc.name as varchar(255)) as foreign_column
, cast(p.name as varchar(255)) as parent_table
, cast(rc.name as varchar(255)) as parent_column
from sysobjects f
inner join sysobjects c on f.parent_obj = c.id
inner join sysreferences r on f.id = r.constid
inner join sysobjects p on r.rkeyid = p.id
inner join syscolumns rc on r.rkeyid = rc.id and r.rkey1 = rc.colid
inner join syscolumns fc on r.fkeyid = fc.id and r.fkey1 = fc.colid
where f.type = 'F'
