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

On Thu, Sep 1, 2016 at 4:28 AM, Michelle Konzack
<linux4michelle(at)gmail(dot)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