Implement 'YEAR' in 'DATE_TRUNC'

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

@@ -458,27 +458,33 @@ public final class DateTimeFunctions {
             dateValue = DateTimeUtils.dateValue(year, month, 1);
             timeNanos = 0l;
             break;
-            
+
         case QUARTER:
-            
+
             long yearForQuarter = DateTimeUtils.yearFromDateValue(dateValue);
             int monthForQuarter = DateTimeUtils.monthFromDateValue(dateValue);
-            
-            
-            if(monthForQuarter >= 10) {
+
+            if (monthForQuarter >= 10) {
                 monthForQuarter = 10;
-            }else if (monthForQuarter >= 7) {
+            } else if (monthForQuarter >= 7) {
                 monthForQuarter = 7;
-            }else if(monthForQuarter >= 4) {
+            } else if (monthForQuarter >= 4) {
                 monthForQuarter = 4;
-            }else {
+            } else {
                 monthForQuarter = 1;
             }
-            
+
             dateValue = DateTimeUtils.dateValue(yearForQuarter, monthForQuarter, 1);
             timeNanos = 0l;
             break;
 
+        case YEAR:
+
+            long yearForYear = DateTimeUtils.yearFromDateValue(dateValue);
+            dateValue = DateTimeUtils.dateValue(yearForYear, 1, 1);
+            timeNanos = 0l;
+            break;
+
         }
         if (timeNanos == null) {
             

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

@@ -818,18 +818,63 @@ SELECT DATE_TRUNC('quarter', '2015-12-29 15:14:13');
 SELECT DATE_TRUNC('QUARTER', '2015-12-29 15:14:13');
 >> 2015-10-01 00:00:00
 
+
 --
--- Test unhandled time unit
+-- Test time unit 'YEAR'
 --
-SELECT DATE_TRUNC('---', '2015-05-29 15:14:13');
-> exception
+select DATE_TRUNC('year', time '00:00:00');
+>> 1970-01-01 00:00:00
+
+select DATE_TRUNC('YEAR', time '00:00:00');
+>> 1970-01-01 00:00:00
+
+select DATE_TRUNC('year', time '15:14:13');
+>> 1970-01-01 00:00:00
+
+select DATE_TRUNC('YEAR', time '15:14:13');
+>> 1970-01-01 00:00:00
+
+select DATE_TRUNC('year', date '2015-05-28');
+>> 2015-01-01 00:00:00
+
+select DATE_TRUNC('YEAR', date '2015-05-28');
+>> 2015-01-01 00:00:00
 
+select DATE_TRUNC('year', timestamp '2015-05-29 15:14:13');
+>> 2015-01-01 00:00:00
 
+select DATE_TRUNC('YEAR', timestamp '2015-05-29 15:14:13');
+>> 2015-01-01 00:00:00
+
+select DATE_TRUNC('year', timestamp with time zone '2015-05-29 15:14:13');
+>> 2015-01-01 00:00:00+00
+
+select DATE_TRUNC('YEAR', timestamp with time zone '2015-05-29 15:14:13');
+>> 2015-01-01 00:00:00+00
+
+select DATE_TRUNC('year', timestamp with time zone '2015-05-29 05:14:13-06');
+>> 2015-01-01 00:00:00-06
+
+select DATE_TRUNC('YEAR', timestamp with time zone '2015-05-29 05:14:13-06');
+>> 2015-01-01 00:00:00-06
+
+select DATE_TRUNC('year', timestamp with time zone '2015-05-29 15:14:13+10');
+>> 2015-01-01 00:00:00+10
+
+select DATE_TRUNC('YEAR', timestamp with time zone '2015-05-29 15:14:13+10');
+>> 2015-01-01 00:00:00+10
 
 SELECT DATE_TRUNC('year', '2015-05-29 15:14:13');
-> exception
+>> 2015-01-01 00:00:00
 
 SELECT DATE_TRUNC('YEAR', '2015-05-29 15:14:13');
+>> 2015-01-01 00:00:00
+
+
+--
+-- Test unhandled time unit
+--
+SELECT DATE_TRUNC('---', '2015-05-29 15:14:13');
 > exception
 
 SELECT DATE_TRUNC('decade', '2015-05-29 15:14:13');