Обсуждение: back slash separated values

What's the version of pgsql?

postgres=# show server_version;
 server_version
----------------
 8.1.0
(1 row)

postgres=# CREATE OR REPLACE FUNCTION foo (v_s1 varchar, v_s2 varchar)
postgres-# RETURNS varchar AS $$
postgres$# BEGIN
postgres$#     RETURN v_s1 || '\\' || v_s2;
postgres$# END;
postgres$# $$ LANGUAGE plpgsql;
CREATE FUNCTION

postgres=# SELECT foo ('pgsql', 'hackers');
      foo
---------------
 pgsql\hackers
(1 row)

Regards,
William ZHANG

"surabhi.ahuja" <surabhi.ahuja@iiitb.ac.in> writes:
> mod_pattern := mod_of_study || ''\\'' ||  $2;

If this is in a function body, you need four backslashes not two, for
the same reason that you need to double the quote marks: one level of
quotes and backslashes is eaten when the function body is parsed as a
string literal.

If you are on a recent PG version, you should consider switching to
dollar-quotes for the function body.  Then you don't need to double
anything, and the constant looks the same as it would look in plain
SQL: mod_of_study || '\\' || $2;

            regards, tom lane