While looking to implement the ODBC replace() function (replace occurences
of $2 in $1 by $3), I found that it could be expressed as:
CREATE FUNCTION replace(text, text, text) RETURNS text AS '
select
case when position($2 in $1) = 0 or char_length($2) = 0
then $1
else substring($1 from 1 for position($2 in $1) - 1)
|| $3
|| replace(substring($1 from position($2 in $1) + char_length($2)),
$2, $3)
end;
' LANGUAGE SQL WITH (isstrict);
Now this command doesn't actually work because it requires the replace()
function to exist already. But it does work if one first creates a stub
replace() function and then uses CREATE OR REPLACE.
(So much about the claim that procedural languages are a security hole
because they allow infinite loops.)
I was wondering whether, as a future project, we could make this more
convenient by parsing the body of the function with the binding of the
function already in effect.
Comments?
--
Peter Eisentraut [EMAIL PROTECTED] http://funkturm.homeip.net/~peter
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