There are a lot of inactive connection in my oracle server. I retrieve SQL text from those inactive. The SQL test is \[code\]SELECT PARAMETER, VALUE FROM SYS.NLS_DATABASE_PARAMETERS WHERE PARAMETER IN ('NLS_CHARACTERSET', 'NLS_NCHAR_CHARACTERSET')\[/code\]but I never use the SQL statement in my system, and do not know why the statement run automatically without closing automatically.