Re: Let-bindings in SQL statements

On 26 January 2012 15:37, Jon Smark <jon(dot)smark(at)yahoo(dot)com> wrote:

> Hi,
>
> Is it possible to do the equivalent of let-bindings in a pure SQL function?
> I have a SELECT that invokes "now" multiple times. It would be nicer
> to do it only once and reuse the value. Something like this:
>
> LET right_now = SELECT now () IN
> SELECT * FROM my_table WHERE right_now >= start AND ...
>
> In PL/pgSQL this is easy, but I wonder about SQL...
>
> Thanks in advance!
> Jon
>
>
In fact now() is a little bit tricky here. now() returns the time when the
transaction started, so if you run `begin;` and call now() multiple times
(even in different queries, but within the same transaction), the function
will return the same value.

regards
Szymon