How about a unique index.
Create unique index table_col2_col3_unique ON table (col2, col3);
> -----Oorspronkelijk bericht-----
> Van: pgsql-general-owner@postgresql.org
> [mailto:pgsql-general-owner@postgresql.org] Namens roverr
> Verzonden: woensdag 5 februari 2003 12:47
> Aan: pgsql-general@postgresql.org
> Onderwerp: [GENERAL] Question: unique on multiple columns
>
>
> I'm running postgresql 7.2.1.
> Is there a way to specify a constraint such that the
> combination of two columns in a table is unique?
>
> I have a table as follows:
> col 1: id, type serial, primary key
> col 2: host_id, type integer, foreign key to hosts table
> col 3: data_time, type timestamp
> col 4 - 9 data that is unique to col 2 and 3
>
> I wish to have a constraint such that the combination
> of the host_id entry in col 2 and each data_time entry
> in col 3 must be unique.
> My thoughts are to calculate a new column based on
> col 2 and 3 and force that to be unique. Is this
> the correct approach or is my table layout hopelessly
> flawed?
>
> Thanks in advance,
> Gary
>
>
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