On Mon, Jan 23, 2017 at 10:34 AM, Corey Huinker <corey.huin...@gmail.com> wrote:
> I was giving some thought to how psql handles undefined variables. > > I would like an option where either psql can provide an alternate value > when an undefined variable is referenced, or a way to detect that a > specific variable is undefined and replace it with a defined variable. > > My first thought thought was to have a > > > \set_if_undefined var_name 'default_value' > > \coalesce var_name [maybe other var names?] 'default_value' --sets the value of var_name to itself or the first defined/non-null result of the subsequent items. Probably only useful if you allow expressions. I have followed the "\if" thread that closely but IIRC that was part of the discussion there. > > Another idea adding a \pset parameter that would return a specific value > when an undefined psql variable is referenced instead of raising an error. > Like this: > > # select :'x' as value_of_x; > ERROR: syntax error at or near ":" > LINE 1: select :'x' as value_of_x; > ^ > > # \pset variable_default '' > analytics=# select :'x' as value_of_x; > value_of_x > ------------ > > (1 row) > > -1 I unconvinced that setting this in the global environment is a good thing. David J.
