求助，oracle监听不断报错

监听不断报错，几天就把空间撑满，错误日志：

TNS-12505: TNS:listener does not currently know of SID given in connect descriptor

09-OCT-2015 10:43:20 * (CONNECT_DATA=(SID=sgdb)(CID=(PROGRAM=JDBC Thin Client)(HOST=__jdbc__)(USER=root))) * (ADDRESS=(PROTOCOL=tcp)(HOST=127.0.0.1)(PORT=50631)) * establish * sgdb * 12505