On Sun, Sep 29, 2019 at 12:40 PM stan <stanb(at)panix(dot)com> wrote:
> I have a table that consists of 3 columns.
>
> vendor_key
> mfg_key
> preferred (boolean)
>
> The idea is that a given vendor is the vendor we want to use for each
> manufacturer for a given project.
>
> I need to constrain such that only on row of mfg, vendor and project can
> be set to TRUE.
>
>
Partial unique index
Example 3 on this page
https://www.postgresql.org/docs/current/indexes-partial.html is exactly
what you are looking for.
John W Higgins
>
>