Re: SQL in constraints II

On Fri, 05 Mar 1999 08:08:15 +0100, GreMa_at_t-online.de (Matthias Gresz) wrote:

>Not necessarily:
>
>SELECT
> field
>FROM
> TABLE t
>WHERE
> t.rowid != :new.rowid
>;
>
>may do well.
>

I just tried this, and it seems only to work in an insert statement. In an update statement, you still get a mutating table error.

You, of course, know that this constraint can be implemented by:

1. create a package to hold a pl/sql table of empnos
2. Use a statement level pre-update/insert trigger to ensure that the pl/sql table of empno's is empty.
3. Use a row-level post-update trigger to populate the table with the empno's being modified
4. Use a statement level post-update trigger to iterate through the pl/sql table, checking for overlapping date ranges.