Implement 'DECADE' 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;
+            TIMEZONE_HOUR = 130, TIMEZONE_MINUTE = 131, DECADE = 132;
 
     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

@@ -8,6 +8,7 @@ package org.h2.util;
 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;
+import static org.h2.expression.Function.DECADE;
 import static org.h2.expression.Function.EPOCH;
 import static org.h2.expression.Function.HOUR;
 import static org.h2.expression.Function.ISO_DAY_OF_WEEK;
@@ -24,7 +25,6 @@ import static org.h2.expression.Function.TIMEZONE_HOUR;
 import static org.h2.expression.Function.TIMEZONE_MINUTE;
 import static org.h2.expression.Function.WEEK;
 import static org.h2.expression.Function.YEAR;
-
 import java.math.BigDecimal;
 import java.text.DateFormatSymbols;
 import java.text.SimpleDateFormat;
@@ -32,7 +32,6 @@ import java.util.GregorianCalendar;
 import java.util.HashMap;
 import java.util.Locale;
 import java.util.TimeZone;
-
 import org.h2.api.ErrorCode;
 import org.h2.expression.Function;
 import org.h2.message.DbException;
@@ -105,6 +104,7 @@ public final class DateTimeFunctions {
         DATE_PART.put("NS", NANOSECOND);
         DATE_PART.put("TIMEZONE_HOUR", TIMEZONE_HOUR);
         DATE_PART.put("TIMEZONE_MINUTE", TIMEZONE_MINUTE);
+        DATE_PART.put("DECADE", DECADE);
     }
 
     /**
@@ -216,7 +216,7 @@ public final class DateTimeFunctions {
     }
 
     /**
-     * Calculate the number of crossed unit boundaries between two timestamps. This
+     * Calculate the number) of crossed unit boundaries between two timestamps. This
      * method is supported for MS SQL Server compatibility.
      * 
      * <pre>
@@ -485,6 +485,14 @@ public final class DateTimeFunctions {
             timeNanos = 0l;
             break;
 
+        case DECADE:
+            
+            long yearForDecade = DateTimeUtils.yearFromDateValue(dateValue);
+            yearForDecade = (long) (Math.floor(yearForDecade / 10) * 10);
+            dateValue = DateTimeUtils.dateValue(yearForDecade, 1, 1);
+            timeNanos = 0l;
+            break;
+            
         }
         if (timeNanos == null) {
             

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

@@ -870,6 +870,62 @@ SELECT DATE_TRUNC('year', '2015-05-29 15:14:13');
 SELECT DATE_TRUNC('YEAR', '2015-05-29 15:14:13');
 >> 2015-01-01 00:00:00
 
+--
+-- Test time unit 'DECADE'
+--
+select DATE_TRUNC('decade', time '00:00:00');
+>> 1970-01-01 00:00:00
+
+select DATE_TRUNC('DECADE', time '00:00:00');
+>> 1970-01-01 00:00:00
+
+select DATE_TRUNC('decade', time '15:14:13');
+>> 1970-01-01 00:00:00
+
+select DATE_TRUNC('DECADE', time '15:14:13');
+>> 1970-01-01 00:00:00
+
+select DATE_TRUNC('decade', date '2015-05-28');
+>> 2010-01-01 00:00:00
+
+select DATE_TRUNC('DECADE', date '2015-05-28');
+>> 2010-01-01 00:00:00
+
+select DATE_TRUNC('decade', timestamp '2015-05-29 15:14:13');
+>> 2010-01-01 00:00:00
+
+select DATE_TRUNC('DECADE', timestamp '2015-05-29 15:14:13');
+>> 2010-01-01 00:00:00
+
+select DATE_TRUNC('decade', timestamp with time zone '2015-05-29 15:14:13');
+>> 2010-01-01 00:00:00+00
+
+select DATE_TRUNC('DECADE', timestamp with time zone '2015-05-29 15:14:13');
+>> 2010-01-01 00:00:00+00
+
+select DATE_TRUNC('decade', timestamp with time zone '2015-05-29 05:14:13-06');
+>> 2010-01-01 00:00:00-06
+
+select DATE_TRUNC('DECADE', timestamp with time zone '2015-05-29 05:14:13-06');
+>> 2010-01-01 00:00:00-06
+
+select DATE_TRUNC('decade', timestamp with time zone '2015-05-29 15:14:13+10');
+>> 2010-01-01 00:00:00+10
+
+select DATE_TRUNC('DECADE', timestamp with time zone '2015-05-29 15:14:13+10');
+>> 2010-01-01 00:00:00+10
+
+SELECT DATE_TRUNC('decade', '2015-05-29 15:14:13');
+>> 2010-01-01 00:00:00
+
+SELECT DATE_TRUNC('DECADE', '2015-05-29 15:14:13');
+>> 2010-01-01 00:00:00
+
+SELECT DATE_TRUNC('decade', '2010-05-29 15:14:13');
+>> 2010-01-01 00:00:00
+
+SELECT DATE_TRUNC('DECADE', '2010-05-29 15:14:13');
+>> 2010-01-01 00:00:00
 
 --
 -- Test unhandled time unit
@@ -877,11 +933,7 @@ SELECT DATE_TRUNC('YEAR', '2015-05-29 15:14:13');
 SELECT DATE_TRUNC('---', '2015-05-29 15:14:13');
 > exception
 
-SELECT DATE_TRUNC('decade', '2015-05-29 15:14:13');
-> exception
 
-SELECT DATE_TRUNC('DECADE', '2015-05-29 15:14:13');
-> exception
 
 SELECT DATE_TRUNC('century', '2015-05-29 15:14:13');
 > exception