# With placeholders
my $sth_test = $dbh->prepare("select distinct cast($date_col as date) from ?;") or die;
$sth_test->execute($schema.$table);

# Errors (on execute())
INFO: The database has been opened successfully.
DBD::Pg::st execute failed: ERROR:  syntax error at or near "$1"
LINE 1: select distinct cast(date as date) from $1;
                                                       ^ at ./refresh_dates.pl line n.
DBD::Pg::st execute failed: ERROR:  syntax error at or near "$1"
LINE 1: select distinct cast(date as date) from $1;
                                                       ^ at ./refresh_dates.pl line n.


# Without placeholders
my $sth_test = $dbh->prepare("select distinct cast($date_col as date) from $schema.$table;") or die;
$sth_test->execute();
$dbh->disconnect();

# Error (on disconnect)
DBI::db=HASH(0x32cec98)->disconnect invalidates 1 active statement handle (either destroy statement handles or call finish on them before disconnecting) at ./refresh_dates.pl line n.