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Posted by Tony Louazι on 10/14/08 11:59
thanx it works !
I thought and I think there's surely another way to get the same result
(without testing a NULL value)
>> > "Tony Louazι" wrote :
>> > > Hi, My SQL lessons are very far :(
>> > >
>> > > CREATE TABLE CONTACTS
>> > > (ID INT,
>> > > NAME VARCHAR(10)
>> > > PHONE VARCHAR(10))
>> > >
>> > > CREATE TABLE CLASS
>> > > (CONTACT INT,
>> > > CAT INT)
>> > >
>> > > INSERT INTO CONTACTS VALUES (101, 'toto', '3545')
>> > > INSERT INTO CONTACTS VALUES (102, 'pif', '8421')
>> > > INSERT INTO CONTACTS VALUES (103, 'loulou', '1245')
>> > >
>> > > INSERT INTO CLASS VALUES (101, 1)
>> > > INSERT INTO CLASS VALUES (101, 2)
>> > > INSERT INTO CLASS VALUES (102, 1)
>> > >
>> > > toto owns to category 1 and 2
>> > > pif owns to category 1
>> > > loulou owns to none categories
>> > >
>> > > => how can I display contacts who own to none categories (like
>> > > loulou)
> ?
>> > >
>> > > I tried:
>> > > SELECT * FROM contacts LEFT OUTER JOIN class ON id = contact
>> > > I get the list of all contacts...
>> > > but if I add 'WHERE cat = NULL' : there's no result :(
>> > >
>> > > Thanx for your help !
>> > >
>> > >
>> >
>> > isn't that what you'd expect? there don't seem to be any null cats in
> what
>> > you show....
>> >
>> >
>>
>> oops! not enough coffee yet! wait one :-)
>>
>
> try
> IS NULL
> in place of
> = NULL
>
> testing for null is a special case
>
>
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