DBD::Pg::st execute failed: execute called with an unbound placeholder at ./refresh_dates.pl line nn.
DBD::Pg::st execute failed: execute called with an unbound placeholder at ./refresh_dates.pl line nn.

# Or:
Can't locate object method "execute" via package "DBI::db" at ./refresh_dates.pl line nn.

##</code><code>##

Global symbol "$prepare" requires explicit package name at ./refresh_dates.pl line nn.
Execution of ./refresh_dates.pl aborted due to compilation errors.

##</code><code>##

my $sth2 = $dbh->$prepare("update $schema.$table set $date_col = $date_new where $where_col = 1;") or die;
$sth2->execute();

##</code><code>##

#!/bin/perl
use strict;
use warnings;
use lib ('./');
use mylib;
use DateTime;
use DateTime::Duration;
use Time::Piece;
use POSIX qw(strftime);

# User-dependent variables
my $db_driver  = 'Pg';                   # `Pg` for psql, `mysql` for mysql
my $username = 'postgres';               # Database user name
my $password = 'password';               # Database user password
my $database = 'mydb';                   # Database name
my $schema_table = 'myschema.mytable';   # Schema.table

# Other variables
my $schema = $schema_table;
my $table = $schema_table;
$schema =~ s/^([^.]*).*$/$1/;
$table  =~ s/^[^.]*.([^.]*)$/$1/;
if ($schema_table =~ /\./){
	$schema =~ s/^([^.]*).*$/$1/;
	$table  =~ s/^[^.]*\.([^.]*)$/$1/;
} else {
	$schema = 'public';
	$table = $schema_table;
	$schema_table = '$schema.$table';
}

my $date_col = "date";
my $where_col = "id";
my ($hours, $minutes, $seconds);
my (@date_time, $temp, $date_new);
my ($year, $month, $day);
my ($date_tbl, time_tbl);
my ($dsn, $dbh, $sth, $sth2);

# Open the database
$dsn = "DBI:$db_driver:dbname = $database";
$dbh = DBI->connect($dsn, $user, $password, { RaiseError => 1 }) or die RED, "ERROR: The database could not be opened.\n       $DBI::errstr\n       Stopped$!";
	print "INFO: The database has been opened successfully.\n";

# Get time from DB
$sth = $dbh->prepare("select $date_col from $schema.$table where $where_col = 1;") or die;
$sth->execute();
$sth->bind_col(1, \$temp);
while ($sth->fetch()) {
	$date_time[0] = $temp;
}

# Get date
$date_tbl = $temp;
$temp =~ /([^-]+)-([^-]+)-([^-]+) /;
($year, $month, $day) = ($1, $2, $3);

# Get hours, minutes, seconds from time
$time_tbl = $temp;
$time_tbl =~ / ([^:]+):([^:]+):([^:]+)[+]/;
($hours, $minutes, $seconds) = ($1, $2, $3);

# Set new date
$date_new = DateTime->today->set_time_zone('Europe/London')->set_hour($hours)->set_minute($minutes)->set_second($seconds)->strftime("%F %T%z");

# Update the dates
$sth2 = $dbh->$prepare("update $schema.$table set $date_col = $date_new where $where_col = 1;") or die;
$sth2->execute();

# Close the database
$dbh->disconnect() or die RED, "ERROR: The database could not be disconnected.\n       $DBI::errstr\n       Stopped$!";