SQL 计算列 http://www.cnblogs.com/wyfs/archive/2012/03/09/2387712.html
SQLSERVER 异常捕捉:http://www.cnblogs.com/qingfengtanying/archive/2011/01/17/1937432.html
SQLSERVER存储过程返回值:http://blog.csdn.net/liangweiwei130/article/details/6691207