Check psql parameter is passed, if not ask for it

[Wiwwo Staff <wiwwo@xxxxxxxxx>]

Hi!

I want to check if I pass the parameter "param1" to a sql script "delme.sql" like

```

\if ':param1'
  \echo :param1;
\else
  \prompt 'Param1? ' :param1
\endif
select :'param1';

```

if parameter `param1` is not passed, the .sql should ask for it.

If I run something like

`psql -f delme.sql -v param1=1`

it works, but if i pass

`psql -f delme.sql -v param1=meh`

i receive

`psql:delme.sql:1: error: unrecognized value ":param1" for "\if _expression_": Boolean expected`

How can I implement that?

TIA, Wiwwo