MySQL date functions

h2/src/tools/org/h2/mode/FunctionsMySQL.java

+/*
+ * Copyright 2004-2008 H2 Group. Multiple-Licensed under the H2 License, 
+ * Version 1.0, and under the Eclipse Public License, Version 1.0
+ * (http://h2database.com/html/license.html).
+ * Initial Developer: Jason Brittain (jason.brittain at gmail.com)
+ */
+package org.h2.mode;
+
+import java.sql.Connection;
+import java.sql.SQLException;
+import java.sql.Statement;
+import java.text.SimpleDateFormat;
+import java.util.Date;
+
+import org.h2.util.StringUtils;
+
+/**
+ * This class implements some MySQL-specific functions.
+ * 
+ * @author Jason Brittain
+ * @author Thomas Mueller
+ */
+public class FunctionsMySQL {
+    
+    /**
+     * The date format of a MySQL formatted date/time.
+     * Example: 2008-09-25 08:40:59
+     */
+    private static final String DATE_TIME_FORMAT = "yyyy-MM-dd HH:mm:ss";
+    
+    /**
+     * Format replacements for MySQL date formats.
+     * See 
+     * http://dev.mysql.com/doc/refman/5.1/en/date-and-time-functions.html#function_date-format
+     */
+    private static final String[] FORMAT_REPLACE = new String[] {
+            "%a", "EEE",
+            "%b", "MMM",
+            "%c", "MM",
+            "%d", "dd",
+            "%e", "d",
+            "%H", "HH",
+            "%h", "hh",
+            "%I", "hh",
+            "%i", "mm",
+            "%j", "DDD",
+            "%k", "H",
+            "%l", "h",
+            "%M", "MMMM",
+            "%m", "MM",
+            "%p", "a",
+            "%r", "hh:mm:ss a",
+            "%S", "ss",
+            "%s", "ss",
+            "%T", "HH:mm:ss",
+            "%W", "EEEE",
+            "%w", "F",
+            "%Y", "yyyy",
+            "%y", "yy",
+            "%%", "%",
+    };
+
+    /**
+     * Register the functionality in the database.
+     * Nothing happens if the functions are already registered.
+     * 
+     * @param conn the connection
+     */
+    public static void register(Connection conn) throws SQLException {
+        String[] init = new String[] {
+            "UNIX_TIMESTAMP", "unixTimestamp",
+            "FROM_UNIXTIME", "fromUnixTime",
+            "DATE", "date",
+        };
+        Statement stat = conn.createStatement();
+        for (int i = 0; i < init.length; i += 2) {
+            String alias = init[i], method = init[i + 1];
+            stat.execute(
+                    "CREATE ALIAS IF NOT EXISTS " + alias + 
+                    " FOR \"" + FunctionsMySQL.class.getName() + "." + method + "\"");
+        }
+    }
+
+    /**
+     * Get the seconds since 1970-01-01 00:00:00 UTC.
+     * See 
+     * http://dev.mysql.com/doc/refman/5.1/en/date-and-time-functions.html#function_unix-timestamp
+     * 
+     * @return the current timestamp in seconds (not milliseconds).
+     */
+    public static int unixTimestamp() {
+        return (int) (System.currentTimeMillis() / 1000L);
+    }
+    
+    /**
+     * Get the seconds since 1970-01-01 00:00:00 UTC of the given timestamp.
+     * See 
+     * http://dev.mysql.com/doc/refman/5.1/en/date-and-time-functions.html#function_unix-timestamp
+     * 
+     * @param timestamp the timestamp
+     * @return the current timestamp in seconds (not milliseconds).
+     */
+    public static int unixTimestamp(java.sql.Timestamp timestamp) throws SQLException {
+        return (int) (timestamp.getTime() / 1000L);
+    }
+        
+    /**
+     * See 
+     * http://dev.mysql.com/doc/refman/5.1/en/date-and-time-functions.html#function_from-unixtime
+     * 
+     * @param seconds The current timestamp in seconds.
+     * @return a formatted date/time String in the format "yyyy-MM-dd HH:mm:ss".
+     */
+    public static String fromUnixTime(int seconds) {
+        SimpleDateFormat formatter = new SimpleDateFormat(DATE_TIME_FORMAT);
+        return formatter.format(new Date(seconds * 1000L));
+    }
+
+    /**
+     * See 
+     * http://dev.mysql.com/doc/refman/5.1/en/date-and-time-functions.html#function_from-unixtime
+     * 
+     * @param seconds The current timestamp in seconds.
+     * @param format The format of the date/time String to return.
+     * @return a formatted date/time String in the given format.
+     */
+    public static String fromUnixTime(int seconds, String format) {
+        format = convertToSimpleDateFormat(format);
+        SimpleDateFormat formatter = new SimpleDateFormat(format);
+        return formatter.format(new Date(seconds * 1000L));
+    }
+    
+    private static String convertToSimpleDateFormat(String format) {
+        String[] replace = FORMAT_REPLACE;
+        for (int i = 0; i < replace.length; i += 2) {
+            format = StringUtils.replaceAll(format, replace[i], replace[i + 1]);
+        }
+        return format;
+    }
+        
+    /**
+     * See
+     * http://dev.mysql.com/doc/refman/5.1/en/date-and-time-functions.html#function_date
+     * This function is dependent on the exact formatting of the MySQL date/time
+     * string.
+     * 
+     * @param dateTime The date/time String from which to extract just the date
+     *            part.
+     * @return the date part of the given date/time String argument.
+     */
+    public static String date(String dateTime) {
+        if (dateTime == null) {
+            return null;
+        }
+        int index = dateTime.indexOf(' ');
+        if (index != -1) {
+            return dateTime.substring(0, index);
+        }
+        return dateTime;
+    }
+        
+}

h2/src/tools/org/h2/mode/package.html

+<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
+<!--
+Copyright 2004-2008 H2 Group. Multiple-Licensed under the H2 License, Version 1.0,,
+and under the Eclipse Public License, Version 1.0
+(http://h2database.com/html/license.html).
+Initial Developer: H2 Group
+-->
+<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en">
+<head><meta http-equiv="Content-Type" content="text/html;charset=utf-8" /><title>
+Javadoc package documentation
+</title></head><body style="font: 9pt/130% Tahoma, Arial, Helvetica, sans-serif; font-weight: normal;">
+
+Utility classes for compatibility with other database, for example MySQL.
+
+</body></html>
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