Find Without primary key Table in SQL Server 2008 R2?
Try this:


SELECT TABLE_NAME FROM information_schema.tables 
WHERE TABLE_NAME 
NOT IN(
SELECT TABLE_NAME from information_schema.table_constraints
WHERE constraint_type = 'Primary Key' )
AND TABLE_TYPE = 'BASE TABLE'


Edit: As per the comment from @MarkSinkinson this query will be wrong in case of Null value  information_schema.table_constraints.table_name, so I would advice the OP to follow with link added in comment which is 


SELECT OBJECT_SCHEMA_NAME( object_id ) as SchemaName, name AS TableName
FROM sys.tables
WHERE OBJECTPROPERTY(object_id,'tablehasprimaryKey') = 0 
ORDER BY SchemaName, TableName ;


to get the list of table not having Primary Key

Know more about this OBJECTPROPERTY which is a better solution here.