Solution 1:

Select Table_name as “Table Without PK”
From Information_schema.Tables
Where Table_type = ‘BASE TABLE’ and
Objectproperty (Object_id(Table_name), ‘TableHasPrimaryKey’) = 0 and

Objectproperty (Object_id(Table_name), ‘IsUserTable’) = 1

Solution 2:

Select [name] as “Table Without PK”

from SysObjects where xtype=’U’ and
id not in
(
Select parent_obj from SysObjects where xtype=’PK’
)