Re: Converting sql anywhere to postgres

I’m fairly confident you can do this using a Rule. It would even be fairly simple.

Be careful, though: Rules are Postgres’ biggest potential foot gun.

Guyren G Howe
On Aug 15, 2023 at 08:05 -0700, Russell Rose | Passfield Data Systems <russellrose(at)passfield(dot)co(dot)uk>, wrote:
> Hi there
>
> I am trying to convert a SQL Anywhere database to postgres. Within SQL anywhere a field can have a default value of ‘last user’. This means that when you perform an update on a table, if the field is not explicitly set then the current user is used. So for instance if I have a field called mod_user in a table, but when I do an update on the table and do not set mod_user then SQL Anywhere sets the field to current_uer. I have tried to replicate this using a postgres trigger in the before update. However, if I do not set the value then it automatically picks up the value that was already in the field. Is there a way to tell the difference between me setting the value to the same as the previous value and postgres automatically picking it up.
>
> If the field myfield contains the word ‘me’. Can I tell the difference between:
> Update table1 set field1=’something’,myfield=’me’
> And
> Update table1 set field1=’something’
>