com presentations: Longhorn PHP date/time talk, now with Quiz: slides/time/basic-parse-time-new.xml slides/time/date-modify-immutable1.xml slides/time/date-modify-immutable2.xml slides/time/date-modify.xml slides/time/date-parse2.xml slides/time/default-timezone.xml slides/time/in-database4.xml slides/time/in-mdb1.xml slides/time/intervals-2.xml slides/time/intervals.xml slides/time/period-2.xml slides/time/queries.jpg slides/time/quiz.xml slides

diff --git a/slides/time/basic-parse-time-new.xml b/slides/time/basic-parse-time-new.xml
index bffa53e..d45a761 100644
--- a/slides/time/basic-parse-time-new.xml
+++ b/slides/time/basic-parse-time-new.xml
@@ -4,7 +4,7 @@
 
 	<blurb>Parsing strings for date time information:</blurb>
 	<example><![CDATA[<?php
-  $dt = new DateTime("2010-03-08 08:43:57");
+  $dt = new DateTime("2018-03-08 08:43:57");
 ?>]]></example>
 <break/>
 
@@ -14,7 +14,7 @@
 <break/>
 
 	<example result="1"><![CDATA[<?php
-  $dt = new DateTime("2010-03-08 08:44:12");
+  $dt = new DateTime("2018-03-08 08:44:12");
   echo $dt->format( 'U' ), "\n";
 ?>]]></example>
 <break/>
diff --git a/slides/time/date-modify-immutable1.xml b/slides/time/date-modify-immutable1.xml
index 2c63a77..5c02e09 100644
--- a/slides/time/date-modify-immutable1.xml
+++ b/slides/time/date-modify-immutable1.xml
@@ -4,7 +4,7 @@
 
 	<blurb>Standard:</blurb>
   <example result="1"><![CDATA[<?php
-  $ts = new DateTime("2014-03-08 15:53:55");
+  $ts = new DateTime("2018-04-17 15:53:55");
   $new = $ts->modify("+2 days");
   echo $ts->format(DateTime::RFC2822), "\n";
   echo $new->format(DateTime::RFC2822), "\n";
diff --git a/slides/time/date-modify-immutable2.xml b/slides/time/date-modify-immutable2.xml
index b0439b0..5339756 100644
--- a/slides/time/date-modify-immutable2.xml
+++ b/slides/time/date-modify-immutable2.xml
@@ -4,7 +4,7 @@
 
 	<blurb>Immutable (new in PHP 5.5):</blurb>
   <example result="1"><![CDATA[<?php
-  $ts = new DateTimeImmutable("2014-03-08 15:53:55");
+  $ts = new DateTimeImmutable("2018-04-17 15:53:55");
   $new = $ts->modify("+2 days");
   echo $ts->format(DateTime::RFC2822), "\n";
   echo $new->format(DateTime::RFC2822), "\n";
diff --git a/slides/time/date-modify.xml b/slides/time/date-modify.xml
index 6cfd505..ae8229f 100644
--- a/slides/time/date-modify.xml
+++ b/slides/time/date-modify.xml
@@ -4,7 +4,7 @@
 
   <example result="0"><![CDATA[<?php
   date_default_timezone_set("Europe/London");
-  $ts = new DateTime("2010-03-08 15:53:55");
+  $ts = new DateTime("2018-03-17 15:53:55");
 
   $ts->modify("+2 days");
 
@@ -16,8 +16,8 @@
 <blurb>Result:</blurb>
   <blurb class='pre'>   Mon, 08 Mar 2010 15:53:55 +0000</blurb>
 
-  <blurb effect="fade-in" class='pre'>   |ef2929|Wed, 10 Mar| 2010 15:53:55 +0000</blurb>
-  <blurb effect="fade-in" class='pre'>   |ef2929|Fri, 02 Apr| 2010 15:53:55 |ef2929|+0100|</blurb>
-  <blurb effect="fade-in" class='pre'>   Fri, |ef2929|09 Apr| 2010 15:53:55 +0100</blurb>
+  <blurb effect="fade-in" class='pre'>   |ef2929|Mon, 19 Mar| 2018 15:53:55 +0000</blurb>
+  <blurb effect="fade-in" class='pre'>   |ef2929|Fri, 13 Apr| 2018 00:00:00 |ef2929|+0100|</blurb>
+  <blurb effect="fade-in" class='pre'>   Fri, |ef2929|20 Apr| 2018 00:00:00 +0100</blurb>
 
 </slide>
diff --git a/slides/time/date-parse2.xml b/slides/time/date-parse2.xml
index da78534..dc867d0 100644
--- a/slides/time/date-parse2.xml
+++ b/slides/time/date-parse2.xml
@@ -2,11 +2,11 @@
 <slide>
   <title>Parsing Dates</title>
 
-  <blurb align='center'>"|a4000000|22||3464a4|apr||f57900|2006| |ad7fa8|8|:|ef2929|36|:|73d216|14| # |c4a000|Europe/Oslo| |75507b|CEST|"</blurb>
+  <blurb align='center'>"|a4000000|22||3464a4|apr||f57900|2018| |ad7fa8|8|:|ef2929|36|:|73d216|14| # |c4a000|Europe/Oslo| |75507b|CEST|"</blurb>
 
 <blurb>Parsing strings with the ~date_parse()~ function:</blurb>
   <example result="1"><![CDATA[<?php
-$date = "22apr2006 8:36:14.43 # Europe/Oslo CEST";
+$date = "22apr2018 8:36:14.43 # Europe/Oslo CEST";
 $t = date_parse( $date );
 
 echo $t['year'], '-', $t['month'], '-', $t['day'], " ";
diff --git a/slides/time/default-timezone.xml b/slides/time/default-timezone.xml
index dcaca11..a769a4d 100644
--- a/slides/time/default-timezone.xml
+++ b/slides/time/default-timezone.xml
@@ -1,25 +1,25 @@
 <?xml version="1.0" encoding="ISO-8859-1"?>
 <slide>
-	<title>Default Timezones</title>
+    <title>Default Timezones</title>
 
-	<blurb>Setting a default timezone:</blurb>
-	<example result="0"><![CDATA[<?php
-	date_default_timezone_set("Europe/Oslo");
-	$ts = new DateTime("1978-12-22 09:15");
-	echo $ts->format("e");
+    <blurb>Setting a default timezone:</blurb>
+    <example result="0"><![CDATA[<?php
+    date_default_timezone_set("Europe/Oslo");
+    $ts = new DateTime("1978-12-22 09:15");
+    echo $ts->format("e");
 ?>]]></example>
 <break/>
 
-	<blurb>Getting a default timezone:</blurb>
-	<example result="0"><![CDATA[<?php
-	$default_identifier = date_default_timezone_get();
-	echo $default_identifier;
+    <blurb>Getting a default timezone:</blurb>
+    <example result="0"><![CDATA[<?php
+    $default_identifier = date_default_timezone_get();
+    echo $default_identifier;
 ?>]]></example>
 <break/>
 
-	<blurb>Default timezone is 'guessed' in the following order:</blurb>
-	<list>
-		<bullet>~date_default_timezone_set()~ value</bullet>
-		<bullet>php.ini's %date.timezone% setting</bullet>
-	</list>
+    <blurb>Default timezone is 'guessed' in the following order:</blurb>
+    <list>
+        <bullet>~date_default_timezone_set()~ value</bullet>
+        <bullet>php.ini's %date.timezone% setting</bullet>
+    </list>
 </slide>
diff --git a/slides/time/in-database4.xml b/slides/time/in-database4.xml
index df8532d..0d22e00 100644
--- a/slides/time/in-database4.xml
+++ b/slides/time/in-database4.xml
@@ -1,26 +1,26 @@
 <slide>
 <title>Storing date/time in a database</title>
-<subtitle>Conclusion</subtitle>
-
-<blurb>If you want to future proof a specific date and time (Oct 1st,
-13:00)-ie, storing a time in *local time*:</blurb>
-<example><![CDATA[{
-	'title' : 'Giving a talk: Advanced Date/Time handling with PHP',
-	'time' : { 
-		'tz': 'America/Montreal',
-		'dt': '2012-10-01 13:00',
-	}
-}]]></example>
-<break />
+<subtitle>Summary</subtitle>
 
 <blurb>If you want to store a time for an appointment for a group of people
 all in different timezones-ie, store a *specific point in time*:</blurb>
 <example><![CDATA[{
 	'title' : 'Meeting about getting rid of Daylight Saving Time',
 	'time' : { 
-		'tz': 'America/Montreal',
-		'ts': 1349110800,
+		'ts': ISODate("2018-04-19 15:27:32"),
+		'tz': 'Europe/London',
 	},
 	'attendees' : [ 'Arthur David Olson', 'Paul Eggert' ],
 }]]></example>
+<break />
+
+<blurb>If you want to future proof a specific date and time (Oct 1st,
+13:00)-ie, storing a time in *local time*:</blurb>
+<example><![CDATA[{
+	'title' : 'Giving a talk: Advanced Date/Time handling with PHP',
+	'time' : { 
+		'dt': '2018-04-18 19:40',
+		'tz': 'Europe/London',
+	}
+}]]></example>
 </slide>
diff --git a/slides/time/in-mdb1.xml b/slides/time/in-mdb1.xml
new file mode 100644
index 0000000..0a1d4cd
--- /dev/null
+++ b/slides/time/in-mdb1.xml
@@ -0,0 +1,31 @@
+<slide>
+<title>Storing date/time in a database</title>
+<subtitle>Query in MongoDB</subtitle>
+
+<example><![CDATA[{
+	'title' : 'Giving a talk: Advanced Date/Time handling with PHP',
+	'time' : { 
+		'ts': ISODate("2018-04-19 15:27:32"), // ms since Epoch
+		'tz': 'Europe/London',
+	}
+}]]></example>
+
+<blurb>Query:</blurb>
+<example><![CDATA[
+db.dates.aggregate( { '$project' : {
+	local_date: {
+		'$dateToString' : {
+			format: '%Y-%m-%d %H:%M:%S',
+			date: '$time.ts',
+			timezone: '$time.tz'
+		}
+	}
+} } );
+]]></example>
+
+<blurb>Result:</blurb>
+<example><![CDATA[{
+	"_id" : ObjectId("5ad8a9148cb588e5ea33f228"),
+	"local_date" : "2018-04-19 16:34:57"
+}]]></example>
+</slide>
diff --git a/slides/time/intervals-2.xml b/slides/time/intervals-2.xml
index 8cb07a9..16902f2 100644
--- a/slides/time/intervals-2.xml
+++ b/slides/time/intervals-2.xml
@@ -4,7 +4,7 @@
 	<blurb>Applying an interval</blurb>
 
 	<example result="0"><![CDATA[<?php
-$d = new DateTimeImmutable( 'Aug 28th, 2009' );
+$d = new DateTimeImmutable( 'Apr 20th, 2018' );
 echo $d->format( "l Y-m-d\n" );
 
 $i = DateInterval::createFromDateString( "next weekday" );
@@ -15,8 +15,8 @@ echo $d->sub( $i )->format( "l Y-m-d\n" );
 ?>]]></example>
 
 <blurb>Result:</blurb>
-	<blurb                  class='pre'>   Friday 2009-08-28</blurb>
-	<blurb effect="fade-in" class='pre'>   Monday 2009-08-31</blurb>
-	<blurb effect="fade-in" class='pre'>   Thursday 2009-05-18</blurb>
+	<blurb                  class='pre'>   Friday 2018-04-20</blurb>
+	<blurb effect="fade-in" class='pre'>   Monday 2018-04-23</blurb>
+	<blurb effect="fade-in" class='pre'>   Wednesday 2018-01-10</blurb>
 
 </slide>
diff --git a/slides/time/intervals.xml b/slides/time/intervals.xml
index a57b1a4..cc32abd 100644
--- a/slides/time/intervals.xml
+++ b/slides/time/intervals.xml
@@ -12,7 +12,7 @@ $i = new DateInterval( 'P3DT6H' );
 
 // from a difference
 $d1 = new DateTimeImmutable();
-$d2 = new DateTimeImmutable( "2014-06-20 11:45 Europe/London" );
+$d2 = new DateTimeImmutable( "2018-04-21 11:00 Europe/London" );
 $i = $d1->diff( $d2 );
 
 // displaying the difference
diff --git a/slides/time/period-2.xml b/slides/time/period-2.xml
index ed25904..b89277f 100644
--- a/slides/time/period-2.xml
+++ b/slides/time/period-2.xml
@@ -4,10 +4,10 @@
 	<subtitle>Iterating over a period</subtitle>
 
 	<example result="1"><![CDATA[<?php
-$db = new DateTimeImmutable( '2013-12-31' );
-$de = new DateTimeImmutable( '2014-12-31' );
+$db = new DateTimeImmutable( '2017-12-31' );
+$de = new DateTimeImmutable( '2018-12-31' );
 $di = DateInterval::createFromDateString(
-	'third tuesday of next month'
+	'first thursday of next month'
 );
 $dp = new DatePeriod(
 	$db, $di, $de, DatePeriod::EXCLUDE_START_DATE
diff --git a/slides/time/queries.jpg b/slides/time/queries.jpg
new file mode 100644
index 0000000..91a4b25
Binary files /dev/null and b/slides/time/queries.jpg differ
diff --git a/slides/time/quiz.xml b/slides/time/quiz.xml
new file mode 100644
index 0000000..3dba512
--- /dev/null
+++ b/slides/time/quiz.xml
@@ -0,0 +1,30 @@
+<slide>
+<title>Quiz Time!</title>
+
+<break lines="4"/>
+
+<div effect="fade-in-out"><blurb class="big-centre">each day has *24&#160;hours*</blurb></div>
+<div effect="fade-in-out"><blurb class="big-centre">each day is *23,&#160;24&#160;or&#160;25 hours*</blurb></div>
+<div effect="fade-in-out"><blurb class="big-centre">every time exists *only once* during a day</blurb></div>
+<div effect="fade-in-out"><blurb class="big-centre">Februari has *29&#160;or&#160;30* days</blurb></div>
+<div effect="fade-in-out"><blurb class="big-centre">every year is *365* days</blurb></div>
+<div effect="fade-in-out"><blurb class="big-centre">every year is *365&#160;or&#160;366* days</blurb></div>
+<div effect="fade-in-out"><blurb class="big-centre">everybody understands what *PI&#160;day* is</blurb></div>
+<div effect="fade-in-out"><blurb class="big-centre">everybody understands what *4/20 means*</blurb></div>
+<div effect="fade-in-out"><blurb class="big-centre">timezones are *whole&#160;hour* offsets from UTC</blurb></div>
+<div effect="fade-in-out"><blurb class="big-centre">timezones are *half&#160;hour* offsets from UTC</blurb></div>
+<div effect="fade-in-out"><blurb class="big-centre">jump *to DST* is around March</blurb></div>
+<div effect="fade-in-out"><blurb class="big-centre">the difference between standard and DST is *an hour*</blurb></div>
+<div effect="fade-in-out"><blurb class="big-centre">DST is always *ahead* of standard time</blurb></div>
+<div effect="fade-in-out"><blurb class="big-centre">each country has *one* timezone</blurb></div>
+<div effect="fade-in-out"><blurb class="big-centre">China spans *5&#160;geographical* timezones</blurb></div>
+<div effect="fade-in-out"><blurb class="big-centre">DST rules stay always the *same*</blurb></div>
+<div effect="fade-in-out"><blurb class="big-centre">DST rules are announced *at&#160;least&#160;a&#160;year* in advance</blurb></div>
+<div effect="fade-in-out"><blurb class="big-centre">DST rules are announced *in&#160;advance*</blurb></div>
+<div effect="fade-in-out"><blurb class="big-centre">PST is *Pacific&#160;Standard&#160;Time*</blurb></div>
+<div effect="fade-in-out"><blurb class="big-centre">a timezone identifier is the capital of a region</blurb></div>
+<div effect="fade-in-out"><blurb class="big-centre">date calculations are easy</blurb></div>
+<div effect="fade-in-out"><blurb class="big-centre">"2018-03-31" plus month is "2018-04-31"</blurb></div>
+<div effect="fade-in-out"><blurb class="big-centre">"2018-03-31" plus month is "2018-04-30"</blurb></div>
+<div effect="fade-in-out"><blurb class="big-centre">every date calculation is reversable</blurb></div>
+</slide>
diff --git a/slides/time/relative-month.xml b/slides/time/relative-month.xml
index ee5fddf..9de0036 100644
--- a/slides/time/relative-month.xml
+++ b/slides/time/relative-month.xml
@@ -4,18 +4,18 @@
 	<subtitle>"previous month" / "next month"</subtitle>
 
 	<example result="1"><![CDATA[<?php
-  $date = new DateTimeImmutable( '2014-01-31 15:48:21' );
+  $date = new DateTimeImmutable( '2018-01-31 15:48:21' );
   echo $date->modify( 'next month' )->format( 'Y-m-d' ), "\n";
 ?>]]></example>
 <break/>
 
 <div effect="hide">
 <blurb>Explanation:</blurb>
-	<blurb effect="fade-out"    class='pre'>   2014-01-31 15:48:21</blurb>
-	<blurb effect="fade-in-out" class='pre'>   2014-|ef2929|02|-31 15:48:21
+	<blurb effect="fade-out"    class='pre'>   2018-01-31 15:48:21</blurb>
+	<blurb effect="fade-in-out" class='pre'>   2018-|ef2929|02|-31 15:48:21
    
    "next month" increases month number by 1</blurb>
-	<blurb effect="fade-in"     class='pre'>   2014-|ef2929|03-03| 15:48:21
+	<blurb effect="fade-in"     class='pre'>   2018-|ef2929|03-03| 15:48:21
 
    February only has 28 days, so days are overflown
    into the next month</blurb>
diff --git a/slides/time/relative-month3.xml b/slides/time/relative-month3.xml
index 7842923..bb804b4 100644
--- a/slides/time/relative-month3.xml
+++ b/slides/time/relative-month3.xml
@@ -4,18 +4,18 @@
 	<subtitle>"first day *of* next month"</subtitle>
 
 	<example result="1"><![CDATA[<?php
-  $date = new DateTimeImmutable( '2014-01-31 15:48:21' );
+  $date = new DateTimeImmutable( '2018-01-31 15:48:21' );
   echo $date->modify( 'first day of next month' )->format( 'Y-m-d' ), "\n";
 ?>]]></example>
 <break/>
 
 <div effect="hide">
 <blurb>Explanation:</blurb>
-	<blurb effect="fade-out"    class='pre'>   2014-01-31 15:48:21</blurb>
-	<blurb effect="fade-in-out" class='pre'>   2014-|ef2929|02|-31 15:48:21
+	<blurb effect="fade-out"    class='pre'>   2018-01-31 15:48:21</blurb>
+	<blurb effect="fade-in-out" class='pre'>   2018-|ef2929|02|-31 15:48:21
    
    "next month" increases month number by 1</blurb>
-	<blurb effect="fade-in"     class='pre'>   2014-02-|ef2929|01| 15:48:21
+	<blurb effect="fade-in"     class='pre'>   2018-02-|ef2929|01| 15:48:21
 
    "first day of" resets the day number to 1</blurb>
 </div>
diff --git a/slides/time/timestamps-suck.xml b/slides/time/timestamps-suck.xml
index 263cf84..c6deae5 100644
--- a/slides/time/timestamps-suck.xml
+++ b/slides/time/timestamps-suck.xml
@@ -3,17 +3,17 @@
 	<title>Unix timestamps and timezones</title>
 
 	<example result="1"><![CDATA[<?php
-  $date = strtotime( '2014-03-07 20:48:21 America/Toronto' );
+  $date = strtotime( '2018-03-07 20:48:21 America/Toronto' );
   echo date( 'Y-m-d', $date ), "\n";
 ?>]]></example>
 
 <div effect="hide">
 <blurb>Explanation:</blurb>
-	<blurb                 >%$d = strtotime('2014-03-07 20:48 America/Toronto');%</blurb>
+	<blurb                 >%$d = strtotime('2018-03-07 20:48 America/Toronto');%</blurb>
 	<blurb effect="fade-in">%$d = |ef2929|1394243280|; // string is turned into a number%</blurb>
 	<blurb effect="fade-in">%echo date('Y-m-d', 1394243280), "\n";%</blurb>
 	<blurb effect="fade-in">Number is converted to a date/time string using the *default* timezone:<br/>
-	%"2014-03-08" |555753|(01:48:21 Europe/London)|%</blurb>
+	%"2018-03-08" |555753|(01:48:21 Europe/London)|%</blurb>
 </div>
 
 </slide>
diff --git a/time-longhorn18.xml b/time-longhorn18.xml
new file mode 100644
index 0000000..34643bd
--- /dev/null
+++ b/time-longhorn18.xml
@@ -0,0 +1,63 @@
+<?xml version="1.0" encoding="utf-8"?>
+<presentation css="10gen-strict.css">
+<topic>Localization and Internationalization</topic>
+<title>Time Zones and Calendars are a PITA</title>
+<event>Longhorn PHP</event>
+<location>Austain, TX, US</location>
+<date>April 21st, 2018</date>
+<speaker>Derick Rethans</speaker>
+<email>[email protected]</email>
+<url>http://derickrethans.nl/talks.html</url>
+<joindin>http://joind.in/23637</joindin>
+<twitter>derickr</twitter>
+
+<slide>slides/mongodb/title.xml</slide>
+<slide>slides/mongodb/me.xml</slide>
+
+<!-- INTRODUCTION -->
+<slide>slides/time/quiz.xml</slide>
+<slide>slides/time/problems-condensed.xml</slide>
+
+<!-- PHP - IMPROVEMENTS -->
+<slide>slides/time/improvements-timezones.xml</slide>
+<slide>slides/time/improvements-more-on-timezones.xml</slide>
+<slide>slides/time/default-timezone.xml</slide>
+<slide>slides/time/timestamps-suck.xml</slide>
+
+<!-- PHP - CODE EXAMPLES -->
+<slide>slides/time/basic-parse-time-new.xml</slide>
+<slide>slides/time/date-parse2.xml</slide>
+<slide>slides/time/date-parse-from-format3.xml</slide>
+<slide>slides/time/date-parse-from-format2.xml</slide>
+
+<!-- DATE EXAMPLES -->
+<slide>slides/time/date-modify.xml</slide>
+<slide>slides/time/date-modify-immutable1.xml</slide>
+<slide>slides/time/date-modify-immutable2.xml</slide>
+<slide>slides/time/timezone-object-1.xml</slide>
+<slide>slides/time/date-timezone.xml</slide>
+<slide>slides/time/timezone-utilities-3.xml</slide>
+
+<!-- INTERVALS and PERIODS -->
+<slide>slides/time/intervals.xml</slide>
+<slide>slides/time/intervals-2.xml</slide>
+<slide>slides/time/relative-month.xml</slide>
+<slide>slides/time/relative-month3.xml</slide>
+<slide>slides/time/period-2.xml</slide>
+
+<!-- STORING in DATABASE -->
+<!-- OLD:
+<slide>slides/time/in-database1.xml</slide>
+<slide>slides/time/in-database2.xml</slide>
+<slide>slides/time/in-database3.xml</slide>
+-->
+<slide>slides/time/in-database4.xml</slide>
+<slide>slides/time/in-mdb1.xml</slide>
+
+<!-- CALENDARS -->
+
+<!-- EXIT -->
+<slide>slides/time/book.xml</slide> <!-- resources -->
+<slide>slides/mongodb/questions.xml</slide>
+<slide>slides/mongodb/resources.xml</slide> <!-- resources -->
+</presentation>