Hier sind diverse Möglichkeiten um zu überprüfen, für welche Tabellen kein Clustered Index definiert wurde:

CREATE TABLE dbo.t(c1 int) -- heap
CREATE TABLE dbo.t1(c1 int PRIMARY KEY) -- cix
CREATE TABLE dbo.t2(c1 int)
GO
CREATE NONCLUSTERED INDEX ix_t2 ON dbo.t2(c1) -- ncix
GO

SELECT
    t1.*
FROM
    sys.tables t1
WHERE NOT EXISTS(SELECT 1
                FROM
                    sys.indexes
                WHERE
                    [object_id] = t1.[object_id] AND
                    TYPE > 0) AND
    OBJECTPROPERTY(t1.[object_id], 'IsMSShipped') = 0 AND
    t1.[name] NOT LIKE 'sys%'

--oder
SELECT
    o.*
FROM
    sys.objects o
WHERE
    OBJECTPROPERTY(o.object_id, 'IsTable') = 1 AND
    OBJECTPROPERTY(o.object_id, 'IsMSShipped') = 0 AND
    OBJECTPROPERTY(o.object_id, 'TableHasIndex') = 0    

DROP TABLE dbo.t
DROP TABLE dbo.t1
DROP TABLE dbo.t2

Ab SQL Server 2005 sähe die Abfrage folgendermassen aus:

SELECT
    *
FROM
    sys.objects O
WHERE
    O.type = 'U' AND
    OBJECTPROPERTY(O.object_id, 'TableHasClustIndex') = 0