用jtds作驱动程序连接SQL Server常常遇到这个问题：
java.sql.SQLException: Network error IOException Connection refused: connect
下午查了一些资料，算是得到一些信息，总结一下。
jtds官方网站解释如下：
Why do I get java.sql.SQLException: "Network error IOException: Connection refused: connect" when trying to get a connection?
The "Connection refused" exception is thrown by jTDS when it is unable to connect to the server. There may be a number of reasons why this could happen:
- The server name is misspelled or the port number is incorrect.
- SQL Server is not configured to use TCP/IP. Either enable TCP/IP from SQL Server's Network Utility app or have jTDS connect via named pipes (see the URL format for information on how to do this).
- There is a firewall blocking port 1433 on the server.
To check whether TCP/IP is enabled and the port is not blocked you can use "telnet <server_host> 1433". Until telnet doesn't connect, jTDS won't either. If you can't figure out why, ask your network administrator for help.
解决问题当然是先按照官网来检查了，于是一步步查下来，发现符合现象2，但是通过网络管理工具察看TCP/IP，正常。而现象确实与上文描述相同，百思不得其解。
于是baidu+google，终于看到有网友说SQL Server 2000需要升级到SP4 SQLServer2000中文版SP4补丁