Merge pull request #937 from ScaY/scay-issue#935

Add "date_trunc" function (only with 'day')

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

@@ -107,7 +107,7 @@ public class Function extends Expression implements FunctionCall {
             SECOND = 114, WEEK = 115, YEAR = 116, CURRENT_DATE = 117,
             CURRENT_TIME = 118, CURRENT_TIMESTAMP = 119, EXTRACT = 120,
             FORMATDATETIME = 121, PARSEDATETIME = 122, ISO_YEAR = 123,
-            ISO_WEEK = 124, ISO_DAY_OF_WEEK = 125;
+            ISO_WEEK = 124, ISO_DAY_OF_WEEK = 125, DATE_TRUNC = 132;
 
     /**
      * Pseudo functions for DATEADD, DATEDIFF, and EXTRACT.
@@ -419,6 +419,7 @@ public class Function extends Expression implements FunctionCall {
                 1, Value.INT);
         addFunction("ISO_DAY_OF_WEEK", ISO_DAY_OF_WEEK,
                 1, Value.INT);
+        addFunction("DATE_TRUNC", DATE_TRUNC, 2, Value.NULL);
         // system
         addFunctionNotDeterministic("DATABASE", DATABASE,
                 0, Value.STRING);
@@ -1493,6 +1494,13 @@ public class Function extends Expression implements FunctionCall {
             break;
         case DATE_DIFF:
             result = ValueLong.get(datediff(v0.getString(), v1, v2));
+            break;
+        case DATE_TRUNC:
+            // Retrieve the time unit (e.g. 'day', 'microseconds', etc.)
+            String timeUnit = StringUtils.toUpperEnglish(v0.getString());
+
+            result = DateTimeUtils.truncateDate(timeUnit, v1);
+
             break;
         case EXTRACT: {
             int field = getDatePart(v0.getString());
@@ -2371,6 +2379,10 @@ public class Function extends Expression implements FunctionCall {
             min = 1;
             max = 2;
             break;
+        case DATE_TRUNC:
+            min = 2;
+            max = 2;
+            break;
         case TO_CHAR:
         case TO_DATE:
             min = 1;

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

@@ -1470,5 +1470,49 @@ public class DateTimeUtils {
         }
         return nanosOfDay - mod;
     }
+    
+    /**
+     * Truncate the given date to 'day'
+     * 
+     * @param timeUnit the time unit (e.g. 'DAY', 'HOUR', etc.)
+     * @param value the date
+     * @return date truncated to 'day'
+     */
+    public static Value truncateDate(String timeUnit, Value value) {
+        Value result = null;
+
+        // Retrieve the dateValue.
+        long[] fieldDateAndTime = DateTimeUtils.dateAndTimeFromValue(value);
+        long dateValue = fieldDateAndTime[0];
+
+        // Case where the date has to be truncated to the day.
+        if (timeUnit.equals("DAY")) {
+
+            if (value instanceof ValueTimestampTimeZone) {
+
+                // Create a new ValueTimestampTimeZone by only setting the
+                // date. The time in nanoseconds since midnight will be set
+                // to 0.
+                ValueTimestampTimeZone vTmp = (ValueTimestampTimeZone) value;
+                result = ValueTimestampTimeZone.fromDateValueAndNanos(vTmp.getDateValue(), 0,
+                        vTmp.getTimeZoneOffsetMins());
+
+            } else {
+
+                // By default, we create a timestamp by setting the
+                // datevalue to the datevalue retrieved and the time in
+                // nanoseconds since midnight to 0.
+                result = ValueTimestamp.fromDateValueAndNanos(dateValue, 0);
+
+            }
+        } else {
+
+            // Return an exception for the other possible value (not yet
+            // supported).
+            throw DbException.getUnsupportedException(timeUnit);
+        }
+
+        return result;
+    }
 
 }

h2/src/test/org/h2/test/scripts/TestScript.java

@@ -147,9 +147,10 @@ public class TestScript extends TestBase {
                 "current-time", "dateadd", "datediff", "dayname",
                 "day-of-month", "day-of-week", "day-of-year", "extract",
                 "formatdatetime", "hour", "minute", "month", "monthname",
-                "parsedatetime", "quarter", "second", "truncate", "week", "year" }) {
+                "parsedatetime", "quarter", "second", "truncate", "week", "year", "date_trunc" }) {
             testScript("functions/timeanddate/" + s + ".sql");
         }
+        
         deleteDb("script");
         System.out.flush();
     }

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

+select DATE_TRUNC('day', time '00:00:00');
+>> 1970-01-01 00:00:00
+
+select DATE_TRUNC('DAY', time '00:00:00');
+>> 1970-01-01 00:00:00
+
+select DATE_TRUNC('day', time '15:14:13');
+>> 1970-01-01 00:00:00
+
+select DATE_TRUNC('DAY', time '15:14:13');
+>> 1970-01-01 00:00:00
+
+select DATE_TRUNC('day', date '2015-05-29');
+>> 2015-05-29 00:00:00
+
+select DATE_TRUNC('DAY', date '2015-05-29');
+>> 2015-05-29 00:00:00
+
+select DATE_TRUNC('day', timestamp '2015-05-29 15:14:13');
+>> 2015-05-29 00:00:00
+
+select DATE_TRUNC('DAY', timestamp '2015-05-29 15:14:13');
+>> 2015-05-29 00:00:00
+
+select DATE_TRUNC('day', timestamp with time zone '2015-05-29 15:14:13');
+>> 2015-05-29 00:00:00+00
+
+select DATE_TRUNC('DAY', timestamp with time zone '2015-05-29 15:14:13');
+>> 2015-05-29 00:00:00+00
+
+select DATE_TRUNC('day', timestamp with time zone '2015-05-29 05:14:13-06');
+>> 2015-05-29 00:00:00-06
+
+select DATE_TRUNC('DAY', timestamp with time zone '2015-05-29 05:14:13-06');
+>> 2015-05-29 00:00:00-06
+
+select DATE_TRUNC('day', timestamp with time zone '2015-05-29 15:14:13+10');
+>> 2015-05-29 00:00:00+10
+
+select DATE_TRUNC('DAY', timestamp with time zone '2015-05-29 15:14:13+10');
+>> 2015-05-29 00:00:00+10
+
+select DATE_TRUNC('day', '2015-05-29 15:14:13');
+>> 2015-05-29 00:00:00
+
+select DATE_TRUNC('DAY', '2015-05-29 15:14:13');
+>> 2015-05-29 00:00:00
+
+SELECT DATE_TRUNC('---', '2015-05-29 15:14:13');
+> exception
+
+SELECT DATE_TRUNC('microseconds', '2015-05-29 15:14:13');
+> exception
+
+SELECT DATE_TRUNC('MICROSECONDS', '2015-05-29 15:14:13');
+> exception
+
+SELECT DATE_TRUNC('milliseconds', '2015-05-29 15:14:13');
+> exception
+
+SELECT DATE_TRUNC('MILLISECONDS', '2015-05-29 15:14:13');
+> exception
+
+SELECT DATE_TRUNC('second', '2015-05-29 15:14:13');
+> exception
+
+SELECT DATE_TRUNC('SECOND', '2015-05-29 15:14:13');
+> exception
+
+SELECT DATE_TRUNC('minute', '2015-05-29 15:14:13');
+> exception
+
+SELECT DATE_TRUNC('MINUTE', '2015-05-29 15:14:13');
+> exception
+
+SELECT DATE_TRUNC('hour', '2015-05-29 15:14:13');
+> exception
+
+SELECT DATE_TRUNC('HOUR', '2015-05-29 15:14:13');
+> exception
+
+SELECT DATE_TRUNC('week', '2015-05-29 15:14:13');
+> exception
+
+SELECT DATE_TRUNC('WEEK', '2015-05-29 15:14:13');
+> exception
+
+SELECT DATE_TRUNC('month', '2015-05-29 15:14:13');
+> exception
+
+SELECT DATE_TRUNC('MONTH', '2015-05-29 15:14:13');
+> exception
+
+SELECT DATE_TRUNC('quarter', '2015-05-29 15:14:13');
+> exception
+
+SELECT DATE_TRUNC('QUARTER', '2015-05-29 15:14:13');
+> exception
+
+SELECT DATE_TRUNC('year', '2015-05-29 15:14:13');
+> exception
+
+SELECT DATE_TRUNC('YEAR', '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
+
+SELECT DATE_TRUNC('CENTURY', '2015-05-29 15:14:13');
+> exception
+
+SELECT DATE_TRUNC('millennium', '2015-05-29 15:14:13');
+> exception
+
+SELECT DATE_TRUNC('MILLENNIUM', '2015-05-29 15:14:13');
+> exception