Implement 'CENTURY' in 'DATE_TRUNC'

h2/src/main/org/h2/expression/Function.java

@@ -107,7 +107,7 @@ public class Function extends Expression implements FunctionCall {
      * Pseudo functions for DATEADD, DATEDIFF, and EXTRACT.
      */
     public static final int MILLISECOND = 126, EPOCH = 127, MICROSECOND = 128, NANOSECOND = 129,
-            TIMEZONE_HOUR = 130, TIMEZONE_MINUTE = 131, DECADE = 132;
+            TIMEZONE_HOUR = 130, TIMEZONE_MINUTE = 131, DECADE = 132, CENTURY = 133;
 
     public static final int DATABASE = 150, USER = 151, CURRENT_USER = 152,
             IDENTITY = 153, SCOPE_IDENTITY = 154, AUTOCOMMIT = 155,

h2/src/main/org/h2/util/DateTimeFunctions.java

@@ -5,6 +5,7 @@
  */
 package org.h2.util;
 
+import static org.h2.expression.Function.CENTURY;
 import static org.h2.expression.Function.DAY_OF_MONTH;
 import static org.h2.expression.Function.DAY_OF_WEEK;
 import static org.h2.expression.Function.DAY_OF_YEAR;
@@ -105,6 +106,7 @@ public final class DateTimeFunctions {
         DATE_PART.put("TIMEZONE_HOUR", TIMEZONE_HOUR);
         DATE_PART.put("TIMEZONE_MINUTE", TIMEZONE_MINUTE);
         DATE_PART.put("DECADE", DECADE);
+        DATE_PART.put("CENTURY", CENTURY);
     }
 
     /**
@@ -493,6 +495,14 @@ public final class DateTimeFunctions {
             timeNanos = 0l;
             break;
             
+        case CENTURY:
+            
+            long yearForCentury = DateTimeUtils.yearFromDateValue(dateValue);
+            yearForCentury = (long) (Math.floor( (yearForCentury - 1) / 100) * 100) + 1;
+            dateValue = DateTimeUtils.dateValue(yearForCentury, 1, 1);
+            timeNanos = 0l;
+            break;
+            
         }
         if (timeNanos == null) {
             

h2/src/test/org/h2/test/scripts/functions/timeanddate/date_trunc.sql

@@ -928,17 +928,72 @@ SELECT DATE_TRUNC('DECADE', '2010-05-29 15:14:13');
 >> 2010-01-01 00:00:00
 
 --
--- Test unhandled time unit
+-- Test time unit 'CENTURY'
 --
-SELECT DATE_TRUNC('---', '2015-05-29 15:14:13');
-> exception
+select DATE_TRUNC('century', time '00:00:00');
+>> 1901-01-01 00:00:00
+
+select DATE_TRUNC('CENTURY', time '00:00:00');
+>> 1901-01-01 00:00:00
+
+select DATE_TRUNC('century', time '15:14:13');
+>> 1901-01-01 00:00:00
+
+select DATE_TRUNC('CENTURY', time '15:14:13');
+>> 1901-01-01 00:00:00
+
+select DATE_TRUNC('century', date '2015-05-28');
+>> 2001-01-01 00:00:00
+
+select DATE_TRUNC('CENTURY', date '2015-05-28');
+>> 2001-01-01 00:00:00
+
+select DATE_TRUNC('century', timestamp '2015-05-29 15:14:13');
+>> 2001-01-01 00:00:00
+
+select DATE_TRUNC('CENTURY', timestamp '2015-05-29 15:14:13');
+>> 2001-01-01 00:00:00
+
+select DATE_TRUNC('century', timestamp with time zone '2015-05-29 15:14:13');
+>> 2001-01-01 00:00:00+00
+
+select DATE_TRUNC('CENTURY', timestamp with time zone '2015-05-29 15:14:13');
+>> 2001-01-01 00:00:00+00
 
+select DATE_TRUNC('century', timestamp with time zone '2015-05-29 05:14:13-06');
+>> 2001-01-01 00:00:00-06
 
+select DATE_TRUNC('CENTURY', timestamp with time zone '2015-05-29 05:14:13-06');
+>> 2001-01-01 00:00:00-06
+
+select DATE_TRUNC('century', timestamp with time zone '2015-05-29 15:14:13+10');
+>> 2001-01-01 00:00:00+10
+
+select DATE_TRUNC('CENTURY', timestamp with time zone '2015-05-29 15:14:13+10');
+>> 2001-01-01 00:00:00+10
 
 SELECT DATE_TRUNC('century', '2015-05-29 15:14:13');
-> exception
+>> 2001-01-01 00:00:00
 
 SELECT DATE_TRUNC('CENTURY', '2015-05-29 15:14:13');
+>> 2001-01-01 00:00:00
+
+SELECT DATE_TRUNC('century', '2199-05-29 15:14:13');
+>> 2101-01-01 00:00:00
+
+SELECT DATE_TRUNC('CENTURY', '2199-05-29 15:14:13');
+>> 2101-01-01 00:00:00
+
+SELECT DATE_TRUNC('century', '2000-05-29 15:14:13');
+>> 1901-01-01 00:00:00
+
+SELECT DATE_TRUNC('CENTURY', '2000-05-29 15:14:13');
+>> 1901-01-01 00:00:00
+
+--
+-- Test unhandled time unit
+--
+SELECT DATE_TRUNC('---', '2015-05-29 15:14:13');
 > exception
 
 SELECT DATE_TRUNC('millennium', '2015-05-29 15:14:13');