You're right it probably does, unless the constraint needs to do a sub-query to get the matching pattern, which would require a trigger.
On Fri, Mar 15, 2019 at 12:05 PM Rob Sargent <robjsarg...@gmail.com> wrote: > > > On Mar 15, 2019, at 12:59 PM, Adrian Klaver <adrian.kla...@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 <mailingl...@unix-solution.de > <mailto:mailingl...@unix-solution.de <mailingl...@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? > >
