On Mon, Aug 20, 2012 at 5:54 PM, Thom Brown <t...@linux.com> wrote: > On 20 August 2012 22:10, Pavel Stehule <pavel.steh...@gmail.com> wrote: > > 2012/8/20 Robert Haas <robertmh...@gmail.com>: > >> On Sun, Aug 19, 2012 at 12:02 PM, Phil Sorber <p...@omniti.com> wrote: > >>> I am providing a patch to allow you to change the output of a boolean > >>> value in psql much like you can do with NULL. A client requested this > >>> feature and we thought it may appeal to someone else in the community. > >>> > >>> The patch includes updated docs and a regression test. The code > >>> changes themselves are pretty simple and straightforward. > >>> > >>> Example from the regression test: > >>> > >>> SELECT true, false; > >>> bool | bool > >>> ------+------ > >>> t | f > >>> (1 row) > >>> > >>> \pset booltrue 'foo' > >>> \pset boolfalse 'bar' > >>> SELECT true, false; > >>> bool | bool > >>> ------+------ > >>> foo | bar > >>> (1 row) > >>> > >>> \pset booltrue 't' > >>> \pset boolfalse 'f' > >>> SELECT true, false; > >>> bool | bool > >>> ------+------ > >>> t | f > >>> (1 row) > >>> > >>> As always, comments welcome. > >> > >> Why not just do it in the SQL? > >> > >> SELECT CASE WHEN whatever THEN 'foo' ELSE 'bar' END AS whatever; > > > > I understand this motivation - although I was more happy with server > > side solution. > > Wouldn't a server-side solution risk breaking many things that depends > on such a representation? You wouldn't be able to pick and choose > what comes out of the server on a per-application basis unless you use > cumbersome CASE clauses in every query that returns boolean data. > > It sounds like keeping it at the application level is the least > disruptive, and there is a precedent for such changes, such as NULL > representation.
On occasions I have wanted psql to emit the full 'True'/'False' words instead of cryptic one-letter t/f, which can get lost on long rows that get wrapped around on screen. Writing long-winded CASE expressions to get the effect is too much for small ad-hoc queries. I thought of inventing a data type whose out-function would emit these strings, and tack a ::mybool to the expression I want modified. But that would break the applications if somebody pasted the same query in an application (JDBC or some such that understands boolean) and expected a boolean data type instead of a text output of an expression. I think there's a merit to psql supporting this feature, because psql is most commonly used for ad-hoc interactive use, and true/false is more human consumable than t/f (I have had a Java developer ask me what was that 't' value in the resultset in psql). -- Gurjeet Singh
