On a MySQL DB, I would like to find a way to force a couple of columns be both null or both not null at the insert / update time. This means that on each record, both columns are null or both columns are not null. Is there any specific constraint, or could I do it just via BEFORE INSERT / BEFORE UPDATE triggers?
In other words, if a column of a record is null and it is updated setting it with a value, also the other column of that record must be updated with a not-null value. If the column is not null already, I can update it with another value (optionally, the other one too), but if I set it as null, the other column too must be set as null by the update query (no "default" settings).