How to use placeholders with "in (...)" clause?

Question

I know I can do this with interpolation. Can I do it using placeholders?

I am getting this error:

DBD::Pg::st execute failed: ERROR:  invalid input syntax for integer: "{"22,23"}" at ./testPlaceHolders-SO.pl line 20.

For this script:

#!/usr/bin/perl -w

use strict;
use DBI;

# Connect to database.

my $dbh = DBI->connect("dbi:Pg:dbname=somedb;host=localhost;port=5432", "somedb", "somedb");

my $typeStr = "22,23";
my @sqlParms = [ $typeStr ];
my $sqlStr = << "__SQL_END";
    SELECT id
    FROM states
    WHERE typeId in (?)
    ORDER BY id;
__SQL_END

my $query = $dbh->prepare($sqlStr);
$query->execute(@sqlParms);

my $id;
$query->bind_columns(\$id);

# Process rows

while ($query->fetch())
{
    print "Id: $id\n";
}

Is there a way around it besides interpolation?

Answer 1

Posting comment as answer, as requested.

Generate your own placeholder string. Like so:

my @nums = (22,23); 
my $placeholder = join ",", ("?") x @nums; 
$query->execute(@nums); 

Answer 2

DBD::PG has support for PostgreSQL arrays, so you can simply write a query like this:

WHERE typeid = ANY( ARRAY[1,2,3] )

or, with a parameter...

WHERE typeid = ANY(?)

Then just use the array support

my @targets = (1,2,3);
# ...
$query->execute(\@targets);

Answer 3

Yes. You must use placeholders for each value, such as IN (?, ?, ?). You can however generate the correct number of question marks using something like this (untested):

my @values = (22, 23, ...);
# will produce "?, ?, ..."
my $in = join ", ", ("?") x @values;
my $sqlStr = "SELECT id FROM states WHERE typeId in ($in) ORDER BY id;";
my $query = $dbh->prepare($sqlStr);
$query->execute(@values);

Note that if you use an ORM such as DBIx::Class instead, this sort of ugly hack gets abstracted away.

Answer 4

You have to build the SQL statement with the correct number of question marks and then set the parameter values. There is no way to bind a list to a single question mark.