"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
