2018-03-05 15:02 GMT+01:00 Pavel Luzanov <p.luza...@postgrespro.ru>: > On 05.03.2018 16:56, Pavel Stehule wrote: > > >> I can't use psql variable in the DO command. Is it intentional behavior? >>> >> >> yes. psql variables living on client side, and are not accessible from >> server side . DO command is executed on server side. >> >> >> But SELECT command also executed on a server side )) >> I thought that the command is sent to the server after variable's >> replacement. >> > > The psql variables are injected into SQL string before execution (before > SQL string is sent to server). But this injection is disabled inside > strings - and body of DO command is passed as string. > > Yes, now I understand this. But at first glance this is not an obvious > behavior. >
It is most correct when you thinking about it. 1. :xx is out of SQL syntax, so can by safely used. There is not risk of unwanted usage. 2. but string literal can contain :xxx symbols and not necessary it means so it should be usage of psql variable - so additional syntax for disabling evaluation should be necessary 3. I understand to request to use psql variables in DO command. But you should remember - body of DO command is string. body of any function is string too. Some unwanted psql variable evaluation in CREATE FUNCTION can be tragic. Unfortunately DO command is half baked - and doesn't support parameters. I am working on schema variables and I hope it will be a solution of this issue: CREATE VARIABLE var as integer; LET var = :psqlintvar; DO $$ BEGIN RAISE NOTICE '%', var; END; $$; > ----- > Pavel Luzanov > Postgres Professional: http://www.postgrespro.com > The Russian Postgres Company > >
