1.lower() 转换成小写
2.length（） 字符长度，返回long
3.ltrim() left trim 空格
4.reverse() 串反转
5.rtrim() right trim 空格
二常用数学函数
6.abs() 取绝对值
7.floor() 和round（）
三日期函数
curdate（） 返回当前日期 返回Hiberante.Date() 注：Hiberante.*表示Hibernate的基本类型，所对应的Mysql的类型就是Mysql的类型
curtime（） 返回当前时间 返回Hiberante.TIME()
current_timestamp() 返回当前时间 返回Hibernate.TIMESTAMP
DATE_FORMAT() 返回当前格式化的字符串的日期 Hibernate.String
线面还有几个非常重要的
DATEDIFF('1997-12-31 23:59:59','1997-12-30');
TO_DAYS(NOW()) - TO_DAYS('1997-10-04 22:23:00') >= 30
就写这么多了，在hibernate中支持的所有的函数如下所示：
registerFunction("datediff", new StandardSQLFunction("datediff", Hibernate.INTEGER) );
registerFunction("timediff", new StandardSQLFunction("timediff", Hibernate.TIME) );
registerFunction("date_format", new StandardSQLFunction("date_format", Hibernate.STRING) );
registerFunction("curdate", new NoArgSQLFunction("curdate", Hibernate.DATE) );
registerFunction("curtime", new NoArgSQLFunction("curtime", Hibernate.TIME) );
registerFunction("current_date", new NoArgSQLFunction("current_date", Hibernate.DATE, false) );
registerFunction("current_time", new NoArgSQLFunction("current_time", Hibernate.TIME, false) );
registerFunction("current_timestamp", new NoArgSQLFunction("current_timestamp", Hibernate.TIMESTAMP, false) );
registerFunction("date", new StandardSQLFunction("date", Hibernate.DATE) );
registerFunction("day", new StandardSQLFunction("day", Hibernate.INTEGER) );
registerFunction("dayofmonth", new StandardSQLFunction("dayofmonth", Hibernate.INTEGER) );
registerFunction("dayname", new StandardSQLFunction("dayname", Hibernate.STRING) );
registerFunction("dayofweek", new StandardSQLFunction("dayofweek", Hibernate.INTEGER) );
registerFunction("dayofyear", new StandardSQLFunction("dayofyear", Hibernate.INTEGER) );
registerFunction("from_days", new StandardSQLFunction("from_days", Hibernate.DATE) );
registerFunction("from_unixtime", new StandardSQLFunction("from_unixtime", Hibernate.TIMESTAMP) );
registerFunction("hour", new StandardSQLFunction("hour", Hibernate.INTEGER) );
registerFunction("last_day", new StandardSQLFunction("last_day", Hibernate.DATE) );
registerFunction("localtime", new NoArgSQLFunction("localtime", Hibernate.TIMESTAMP) );
registerFunction("localtimestamp", new NoArgSQLFunction("localtimestamp", Hibernate.TIMESTAMP) );
registerFunction("microseconds", new StandardSQLFunction("microseconds", Hibernate.INTEGER) );
registerFunction("minute", new StandardSQLFunction("minute", Hibernate.INTEGER) );
registerFunction("month", new StandardSQLFunction("month", Hibernate.INTEGER) );
registerFunction("monthname", new StandardSQLFunction("monthname", Hibernate.STRING) );
registerFunction("now", new NoArgSQLFunction("now", Hibernate.TIMESTAMP) );
registerFunction("quarter", new StandardSQLFunction("quarter", Hibernate.INTEGER) );
registerFunction("second", new StandardSQLFunction("second", Hibernate.INTEGER) );
registerFunction("sec_to_time", new StandardSQLFunction("sec_to_time", Hibernate.TIME) );
registerFunction("sysdate", new NoArgSQLFunction("sysdate", Hibernate.TIMESTAMP) );
registerFunction("time", new StandardSQLFunction("time", Hibernate.TIME) );
registerFunction("timestamp", new StandardSQLFunction("timestamp", Hibernate.TIMESTAMP) );
registerFunction("time_to_sec", new StandardSQLFunction("time_to_sec", Hibernate.INTEGER) );
registerFunction("to_days", new StandardSQLFunction("to_days", Hibernate.LONG) );
registerFunction("unix_timestamp", new StandardSQLFunction("unix_timestamp", Hibernate.LONG) );
registerFunction("utc_date", new NoArgSQLFunction("utc_date", Hibernate.STRING) );
registerFunction("utc_time", new NoArgSQLFunction("utc_time", Hibernate.STRING) );
registerFunction("utc_timestamp", new NoArgSQLFunction("utc_timestamp", Hibernate.STRING) );
registerFunction("week", new StandardSQLFunction("week", Hibernate.INTEGER) );
registerFunction("weekday", new StandardSQLFunction("weekday", Hibernate.INTEGER) );
registerFunction("weekofyear", new StandardSQLFunction("weekofyear", Hibernate.INTEGER) );
registerFunction("year", new StandardSQLFunction("year", Hibernate.INTEGER) );
registerFunction("yearweek", new StandardSQLFunction("yearweek", Hibernate.INTEGER) );
My SQL在Hibernate中常用函数