Re: check constraint question

On 04/08/2014 03:17 PM, Rob Sargent wrote:
> On 04/08/2014 03:09 PM, CS_DBA wrote:
>>
>> On 04/08/2014 02:58 PM, Rob Sargent wrote:
>>> On 04/08/2014 02:51 PM, CS_DBA wrote:
>>>> Hi All
>>>>
>>>> we have a table like so:
>>>>
>>>>
>>>> customer (
>>>> cust_id integer not null primary key,
>>>> cust_group_id integer not null,
>>>> group_account_id integer not null,
>>>> cust_name varchar not null,
>>>>
>>>> ...
>>>> )
>>>>
>>>> we want to force the cust_group_id to be unique across all
>>>> group_account_id's but not necessarily across the entire table
>>>>
>>>> I assume the best approach would be a check constraint yes? Will
>>>> this be excessively poor per performance if the table gets big?
>>>>
>>>> Thoughts?
>>>>
>>>> Thanks in advance
>>>>
>>>>
>>>>
>>>>
>>>>
>>> A unique index on cust_group_id and group_account_id doesn't do it
>>> for you?
>>>
>> oh right! duh! It's been one of those days....
>>
>>
>>
>>
>>
> Which column goes first depends on your lookup expectations.

Thanks!

Here's another one:

customer (
cust_id integer not null primary key,
cust_group_id integer not null,
group_account_id integer not null,
cust_name varchar not null,
cust_template_id integer,
...
)

If cust_template_id IS NOT NULL then it must reference a valid cust_id

Check constraint?