Question

A little background:
I have a perl script which is performing a number of operations inside of a loop.

Inside of the loop, I create a prepared statement like so:

  // inside loop
  my $statement = "select xxxx from zzzzzz where $foobar;";
  my $query = $connect->prepare($statement);
  $query->execute();

$foobar is updated to a new value everytime the loop completes, which is why i want to change the query every run, however I am getting an error when I try to do so.

When the script is run I get this error:

  DBD::Pg::st execute failed: ERROR:  prepared statement "xxxxxxxxxxxxx" already exists at 

Because I am passing a variable which is updated every time the loop runs, and assuming I need to use this prepared statement, how do I get around this error?

Thank you for your time.

Edit:

For future people having this problem, check this out here :

I was trying to get

my $sth = $dbh->prepare('select interval ?');

http://gborg.postgresql.org/pipermail/dbdpg-general/2006-January/001972.html

http://gborg.postgresql.org/pipermail/dbdpg-general/2006-February/002007.html

list some workarounds: either turning off the server-side prepares
through the pg_server_prepare flag or using eg. ‘?::interval’ instead of
‘interval ?’

Answer 1

Move your prepared statement outside of the loop. If you have a variable that needs to be passed to the prepared statement, you’ll use the ? marker to pass in the variable to the prepared statement. Here’s an example:

my $stmt = $dbh->prepare('SELECT * FROM table WHERE id = ?');
foreach ... {

    my $var = <something>;
    $stmt->execute($var);
}

Here, the prepared statement is created once, and the ? is used to pass in variables. When you call execute, you pass in the variable as parameters.