Re: Conditional INSERT

On Mar 15, 2019, at 12:59 PM, Adrian Klaver <adrian.klaver@aklaver.com> wrote:

On 3/15/19 11:54 AM, basti wrote:

this is a dns database, and the client is update the _acme-challenge for
LE certificates. I don't want that the client can insert "any" txt record.
the client should only insert data if the hostname start with
_acme-challenge. i have no control on client.
i have try this rule but the server reject this with a endless loop:

To borrow a quote:

"I had a problem so I decided to use a rule, now I have two problems."

Do not use a rule. As suggested upstream use a BEFORE INSERT trigger, you will be a lot happier.

CREATE RULE insert_acme AS ON INSERT TO t_dnsadmin_records_txt
    WHERE NEW.hostname like '_acme-challenge%'
    DO INSERT INTO t_dnsadmin_records_txt VALUES (
                                    NEW.domainid,
                                    NEW.hostname,
                                    NEW.txtdata
                                );
On 15.03.19 19:17, Michael Lewis wrote:

    On Fri, Mar 15, 2019 at 10:55 AM basti <mailinglist@unix-solution.de
    <mailto:mailinglist@unix-solution.de>> wrote:

        Hello,

        I want to insert data into table only if condition is true.
        For example:

        INSERT into  mytable (domainid, hostname, txtdata)
          VALUES (100,'_acme.challenge.example', 'somedata');

 Alternative to a trigger implementation, if you are generating that
INSERT statement, you can change it to use a sub-select or CTE that
contains no values if the domainid isn't what you like. If you want it
to fail with error, you could add a check constraint. We might need more
context on what you are doing and why to give good advice.

Does a check constraint not suffice in this situation?