SQL Server: sys.objects

type, type_desc

type is a one or two letter abbreviation that defines the type of the object. type_desc is the human readable form for that type.

select
   count(*),
   type,
   type_desc
from
   sys.objects
group by
   type,
   type_desc
order by
   type;

For example, type PK is a primary key and UQ a unique constraint.

Some information about these two types are found in sys.key_constraints.