H2ExtDialect.java

package org.springside.examples.showcase.orm.hibernate;

import org.hibernate.Hibernate;
import org.hibernate.dialect.H2Dialect;
import org.hibernate.dialect.function.SQLFunctionTemplate;
import org.hibernate.dialect.function.StandardSQLFunction;

/**
 * 演示扩展H2Dialect,增加两种新函数.
 * 
 * @author calvin
 */
public class H2ExtDialect extends H2Dialect {

	public H2ExtDialect() {
		super();
		//新函数up(), 等同于uppper()的缩写, 如where up(u.name)="FOO".
		registerFunction("up", new StandardSQLFunction("upper"));
		//新函数sample(),用于按某个百分比随机决定是否返回该条数据, 如where sample()>50  按50%概率返回数据.
		registerFunction("sample", new SQLFunctionTemplate(Hibernate.DOUBLE, "rand()*100", true));
	}
}