Tom, Jerry, I'm going to do the same as the `quote_identifier` function of Postgres does, only quote if necessary.
Thanks for your explanation, Roman. On Tue, Mar 29, 2016 at 1:31 AM, Jerry Sievers <gsiever...@comcast.net> wrote: > Roman Scherer <ro...@burningswell.com> writes: > > > Hello, > > > > I'm building a DSL in Clojure for SQL and specifically PostgreSQL > > [1]. When building a SQL statement that contains a function call > > I always quote the function name with \" in case the function > > name contains any special characters. Here's an example: > > > > (select db ['(upper "x")]) > > ;=> ["SELECT \"upper\"(?)" "x"] > > > > This worked fine so far, but today I found a case that doesn't > > work as expected, the COALESCE function. > > > > (select db ['(coalesce nil 0)]) > > ;=> ["SELECT \"coalesce\"(NULL, 0)"] > > > > Can someone explain to me what's the difference between quoting > > the `upper` and the `coalesce` function? I can execute the > > following statements via psql, and it works as expected: > > > > SELECT upper ('x'); > > SELECT "upper"('x'); > > SELECT coalesce(NULL, 1); > > > > But as soon as I try this with `coalesce` I get an error: > > > > SELECT "coalesce"(NULL, 1); > > > While not a precise answer to your question, it may be of interest to > note that coalesce is *not* a function. > > It is a language construct with a function-like syntax. > > select distinct proname from pg_proc where proname in ('coalesce', > 'lower'); > proname > --------- > lower > (1 row) > > > > > ERROR: function coalesce(unknown, integer) does not exist > > LINE 1: SELECT "coalesce"(NULL, 1); > > ^ > > HINT: No function matches the given name and argument types. You > might need to add explicit type casts. > > > > What I found so far is, that the `upper` function can be found in > > the `pg_proc` table but not `coalesce`. > > > > SELECT proname FROM pg_proc WHERE proname ILIKE 'upper'; > > SELECT proname FROM pg_proc WHERE proname ILIKE 'coalesce'; > > > > Does this mean that `coalesce` isn't a classical function and I > > shouldn't quote it? Is it instead a keyword, as described in > > the "Lexical Structure" section of the docs [2]? How can I find > > out which other functions are not meant to be quoted? > > > > I'm aware that I do not need to quote the `coalesce` and `upper` > > functions and I may change my strategy for quoting functions names. > > > > Thanks for you help, Roman. > > > > [1] https://github.com/r0man/sqlingvo > > [2] > http://www.postgresql.org/docs/current/static/sql-syntax-lexical.html > > > > -- > Jerry Sievers > Postgres DBA/Development Consulting > e: postgres.consult...@comcast.net > p: 312.241.7800 >