SQLBuilder sqlBuilder = transaction.getSQLBuilderFactory("SampleDataSource").create("");
try{
/* 开始事务 */
transaction.begin();
/* 直接执行SQL查询语句 */
return (List)sqlExecutor.execute(sqlBuilder.constructSQLForCount("messages", "*", "MsgCount", null));
}finally{
/* 关闭事务 */
transaction.close();
}