Thread: COL unique (CustomerID) plus COL unique (COUNT) inside CustomerID

Hello to all,

after a period of silence from Debian, Courier, PHP and PostgreSQL I  am
half back and running into a problem...  :-/

I need a table with an UNIQUE CustomerID which is working fine...

...BUT I need also a second column with a count, which  must  be  UNIQUE
inside the CustomerID.

In clear this:

    CustID       Count
         1           1
         1           2
         1           3

         2           1
         2           2

         3           1
         3           2
         3           3
         ...

How to do this?

Thanks in avance

--
Michelle Konzack        ITSystems
GNU/Linux Developer     0033-6-61925193

On Thu, 2016-09-01 at 12:28 +0300, Michelle Konzack wrote:
> Hello to all,
>
> after a period of silence from Debian, Courier, PHP and PostgreSQL
> I  am
> half back and running into a problem...  :-/
>
> I need a table with an UNIQUE CustomerID which is working fine...
>
> ...BUT I need also a second column with a count,
> which  must  be  UNIQUE
> inside the CustomerID.
>
> In clear this:
>
>     CustID       Count
>          1           1
>          1           2
>          1           3
>
>          2           1
>          2           2
>
>          3           1
>          3           2
>          3           3
>          ...
>
> How to do this?
>
> Thanks in avance
>
> -- 
> Michelle Konzack        ITSystems
> GNU/Linux Developer     0033-6-61925193
>
>


Hi,

(I wouldn't name a column "count").


SELECT MAX(count_er) FROM my_customer_table WHERE cust_id = $1;

Add one to the result. Do INSERT.

As SELECT MAX is a GROUP function it will return zero if the cust_id
doesn't exist.

HTH,

Rob

Michelle Konzack <linux4michelle@gmail.com> wrote:

> Hello to all,
>
> after a period of silence from Debian, Courier, PHP and PostgreSQL I  am
> half back and running into a problem...  :-/
>
> I need a table with an UNIQUE CustomerID which is working fine...
>
> ...BUT I need also a second column with a count, which  must  be  UNIQUE
> inside the CustomerID.
>
> In clear this:
>
>     CustID       Count
>          1           1
>          1           2
>          1           3
>
>          2           1
>          2           2
>
>          3           1
>          3           2
>          3           3
>          ...
>
> How to do this?

don't store the Count-column and using row_number() over (partition by
CustId) instead?

Btw.: Greetings, how are you? ;-)


Regards, Andreas Kretschmer
--
Andreas Kretschmer
http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

On Thu, Sep 1, 2016 at 4:28 AM, Michelle Konzack
<linux4michelle@gmail.com> wrote:

> I need a table with an UNIQUE CustomerID which is working fine...
>
> ...BUT I need also a second column with a count, which  must  be  UNIQUE
> inside the CustomerID.

Just to be clear, you probably have a customer table with "CustIomerId"
as its key and are talking about a "child"of that where you want a
2-column key?

> In clear this:
>
>     CustID       Count
>          1           1
>          1           2
>          1           3
>
>          2           1
>          2           2
>
>          3           1
>          3           2
>          3           3
>          ...
>
> How to do this?

If, for example, the child table is a list of customer contacts,
you might add a "LastContactNo" column to the customer table,
defaulting to zero on customer insert, and which you increment to
get values for the second key column in the contact table.

--
Kevin Grittner
EDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company