Well, DBI, Perl's standard way of interfacing with databases, lets you do just that. You can make an SQL statement with parameters that can be set later:

my $dbh = DBI->connect(...connection parameters...);

my $get_foo = $dbh->prepare("select foo from table where bar=?");

$get_foo->execute(3);  #select foo where bar=3
$get_foo->execute($baz);  #select foo where bar=$baz
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Perhaps you meant something different by constructing a query. If so, you need to specify what you mean. SQL is a whole programming language in itself.