Merge pull request #845 from ScaY/scay-issue#832

add epoch in extract function

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

@@ -10,6 +10,7 @@ import java.io.IOException;
 import java.io.InputStream;
 import java.io.InputStreamReader;
 import java.io.Reader;
+import java.math.BigDecimal;
 import java.nio.charset.StandardCharsets;
 import java.sql.Connection;
 import java.sql.ResultSet;
@@ -61,6 +62,7 @@ import org.h2.value.ValueArray;
 import org.h2.value.ValueBoolean;
 import org.h2.value.ValueBytes;
 import org.h2.value.ValueDate;
+import org.h2.value.ValueDecimal;
 import org.h2.value.ValueDouble;
 import org.h2.value.ValueInt;
 import org.h2.value.ValueLong;
@@ -69,6 +71,7 @@ import org.h2.value.ValueResultSet;
 import org.h2.value.ValueString;
 import org.h2.value.ValueTime;
 import org.h2.value.ValueTimestamp;
+import org.h2.value.ValueTimestampTimeZone;
 import org.h2.value.ValueUuid;
 
 /**
@@ -111,6 +114,11 @@ public class Function extends Expression implements FunctionCall {
      * Pseudo function for {@code EXTRACT(MILLISECOND FROM ...)}.
      */
     public static final int MILLISECOND = 126;
+    
+    /**
+     * Pseudo function for {@code EXTRACT(EPOCH FROM ...)}.
+     */
+    public static final int  EPOCH = 127;
 
     public static final int DATABASE = 150, USER = 151, CURRENT_USER = 152,
             IDENTITY = 153, SCOPE_IDENTITY = 154, AUTOCOMMIT = 155,
@@ -197,6 +205,7 @@ public class Function extends Expression implements FunctionCall {
         DATE_PART.put("S", SECOND);
         DATE_PART.put("MILLISECOND", MILLISECOND);
         DATE_PART.put("MS", MILLISECOND);
+        DATE_PART.put("EPOCH", EPOCH);
 
         // SOUNDEX_INDEX
         String index = "7AEIOUY8HW1BFPV2CGJKQSXZ3DT4L5MN6R";
@@ -1493,7 +1502,57 @@ public class Function extends Expression implements FunctionCall {
             break;
         case EXTRACT: {
             int field = getDatePart(v0.getString());
-            result = ValueInt.get(getDatePart(v1, field));
+            
+            // Normal case when we don't retrieve the EPOCH time
+            if (field != EPOCH) {
+                
+                result = ValueInt.get(getDatePart(v1, field));
+                
+            } else {
+                
+                // Case where we retrieve the EPOCH time.
+                // First we retrieve the dateValue and his time in nanoseconds.
+                long[] a = DateTimeUtils.dateAndTimeFromValue(v1);
+                long dateValue = a[0];
+                long timeNanos = a[1];
+                // We compute the time in nanoseconds and the total number of days.
+                BigDecimal timeNanosBigDecimal = new BigDecimal(timeNanos);
+                BigDecimal numberOfDays = new BigDecimal(DateTimeUtils.absoluteDayFromDateValue(dateValue));
+                BigDecimal nanosSeconds = new BigDecimal(1_000_000_000);
+                BigDecimal secondsPerDay = new BigDecimal(DateTimeUtils.SECONDS_PER_DAY);
+                
+                // Case where the value is of type time e.g. '10:00:00'
+                if (v1 instanceof ValueTime) {
+                    
+                    // In order to retrieve the EPOCH time we only have to convert the time 
+                    // in nanoseconds (previously retrieved) in seconds.
+                    result = ValueDecimal.get(timeNanosBigDecimal.divide(nanosSeconds));
+                    
+                } else if (v1 instanceof ValueDate) {
+                    
+                    // Case where the value is of type date '2000:01:01', we have to retrieve the total 
+                    // number of days and multiply it by the number of seconds in a day.
+                    result = ValueDecimal.get(numberOfDays.multiply(secondsPerDay));
+                    
+                } else if (v1 instanceof ValueTimestampTimeZone) {
+                    
+                    // Case where the value is a of type ValueTimestampTimeZone ('2000:01:01 10:00:00+05).
+                    // We retrieve the time zone offset in minute
+                    ValueTimestampTimeZone v = (ValueTimestampTimeZone) v1;
+                    BigDecimal timeZoneOffsetSeconds = new BigDecimal(v.getTimeZoneOffsetMins() * 60);
+                    // Sum the time in nanoseconds and the total number of days in seconds 
+                    // and adding the timeZone offset in seconds.
+                    result = ValueDecimal.get(timeNanosBigDecimal.divide(nanosSeconds)
+                            .add(numberOfDays.multiply(secondsPerDay))
+                            .subtract(timeZoneOffsetSeconds));
+                    
+                } else {
+                    
+                    // By default, we have the date and the time ('2000:01:01 10:00:00) if no type is given. 
+                    // We just have to sum the time in nanoseconds and the total number of days in seconds.
+                    result = ValueDecimal.get(timeNanosBigDecimal.divide(nanosSeconds).add(numberOfDays.multiply(secondsPerDay)));
+                }
+            }
             break;
         }
         case FORMATDATETIME: {

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

@@ -36,6 +36,11 @@ public class DateTimeUtils {
      * The number of milliseconds per day.
      */
     public static final long MILLIS_PER_DAY = 24 * 60 * 60 * 1000L;
+    
+    /**
+     * The number of seconds per day.
+     */
+    public static final long SECONDS_PER_DAY = 24 * 60 * 60;
 
     /**
      * UTC time zone.

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

@@ -92,6 +92,7 @@ public class TestScript extends TestBase {
         } else {
             decimal2 = "decimal_numeric";
         }
+        
         for (String s : new String[] { "array", "bigint", "binary", "blob",
                 "boolean", "char", "clob", "date", "decimal", decimal2, "double", "enum",
                 "geometry", "identity", "int", "other", "real", "smallint",

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

@@ -2,3 +2,42 @@
 -- and the EPL 1.0 (http://h2database.com/html/license.html).
 -- Initial Developer: H2 Group
 --
+
+select EXTRACT (EPOCH from time '00:00:00');
+> 0
+
+select EXTRACT (EPOCH from time '10:00:00');
+> 36000
+
+select EXTRACT (EPOCH from time '10:00:00.123456');
+> 36000.123456
+
+select EXTRACT (EPOCH from date '1970-01-01');
+> 0
+
+select EXTRACT (EPOCH from date '2000-01-03');
+> 946857600
+
+select EXTRACT (EPOCH from timestamp '1970-01-01 00:00:00');
+> 0
+
+select EXTRACT (EPOCH from timestamp '1970-01-03 12:00:00.123456');
+> 216000.123456
+
+select EXTRACT (EPOCH from timestamp '2000-01-03 12:00:00.123456');
+> 946900800.123456
+
+select EXTRACT (EPOCH from timestamp '2500-01-03 12:00:00.654321');
+> 16725441600.654321
+
+select EXTRACT (EPOCH from timestamp with time zone '1970-01-01 00:00:00+05');
+> -18000
+
+select EXTRACT (EPOCH from timestamp with time zone '1970-01-03 12:00:00.123456+05');
+> 198000.123456
+
+select EXTRACT (EPOCH from timestamp with time zone '2000-01-03 12:00:00.123456+05');
+> 946882800.123456
+
+select extract(EPOCH from '2001-02-03 14:15:16');
+> 981209716