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: 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@xxxxxxxxxxxxxxxx > <mailto:mailinglist@xxxxxxxxxxxxxxxx>> 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.