数据库连接控制
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在数据库上下文中，一个 Session代表一个用户进程（或应用程序进程）与数据库服务器建立的一个连接通道及其执行上下文。其生命周期表示：当用户使用有效的凭据（用户名/密码）连接到数据库时，一个Session被创建。当用户显式断开连接（如执行 DROP SESSION）、应用程序关闭连接、连接超时或管理员强制终止时，Session结束，目标Session会立即（或在数据库内部处理后尽快）被终止，与该Session关联的所有操作将被停止。可通过系统表SYS_SESSIONS字段SESSION_ID查看连接号。
一、删除连接
1.1 语法格式
1.2 参数说明
ICONST：连接号。
示例：
SQL
-- 通过系统表SYS_SESSIONS查看当前连接数
SQL> SELECT * FROM SYS_SESSIONS;
+--------+------------+---------+-----------+--------------+----------------+-----------+--------+-------+---------+---------------+--------------------------+--------------------------+--------+----------+----------+-------------+-----------+--------------------------+--------------------------+------------+----------+----------+-----------+-----------------------+--------------+---------------+---------+----------+--------------+---------------+------------------+---------+-------------------+----------------+-----------------+---------------+------------+----------------+---------------+----------+----------------+--------+
| NODEID | SESSION_ID | USER_ID | USER_NAME | CURR_USER_ID | CURR_USER_NAME | SCHEMA_ID | SCHEMA | DB_ID | DB_NAME | IP | START_T | VISIT_T | STATUS | CURR_TID | CURR_CID | AUTO_COMMIT | ISO_LEVEL | TRANS_START_T | CMD_START_T | CURSOR_NUM | MEM_SIZE | CHAR_SET | TIME_ZONE | TIME_FORMAT | LOCK_TIMEOUT | STRICT_COMMIT | RESULT | LANGUAGE | RETURN_ROWID | RETURN_SCHEMA | RETURN_CURSOR_ID | LOB_RET | EMPTY_STR_AS_NULL | OPTIMIZER_MODE | COMPATIBLE_MODE | FILTER_POLICY | TRANS_RDLY | DISABLE_BINLOG | IDENTITY_MODE | APP_NAME | KEYWORD_FILTER | SQL |
+--------+------------+---------+-----------+--------------+----------------+-----------+--------+-------+---------+---------------+--------------------------+--------------------------+--------+----------+----------+-------------+-----------+--------------------------+--------------------------+------------+----------+----------+-----------+-----------------------+--------------+---------------+---------+----------+--------------+---------------+------------------+---------+-------------------+----------------+-----------------+---------------+------------+----------------+---------------+----------+----------------+--------+
| 1 | 5 | 1 | SYSDBA | 1 | SYSDBA | 1 | SYSDBA | 1 | SYSTEM | 192.168.2.236 | 2025-07-11 09:20:00.000 | 2025-07-11 09:20:56.000 | 112 | <NULL> | 0 | T | 1 | <NULL> | <NULL> | 0 | 262144 | UTF8 | GMT+08:00 | YYYY-MM-DD HH24:MI:SS | 0 | F | DEFAULT | PL/SQL | F | F | F | F | F | ALL_ROWS | NONE | 0 | F | F | DEFAULT | | <NULL> | <NULL> |
| 1 | 6 | 1 | SYSDBA | 1 | SYSDBA | 1 | SYSDBA | 1 | SYSTEM | 192.168.2.236 | 2025-07-11 09:25:49.000 | 2025-07-11 09:26:02.000 | 114 | 1125 | 5 | T | 1 | 2025-07-11 09:26:02.000 | 2025-07-11 09:26:02.000 | 0 | 262144 | UTF8 | GMT+08:00 | YYYY-MM-DD HH24:MI:SS | 0 | F | DEFAULT | PL/SQL | F | F | F | F | F | ALL_ROWS | NONE | 0 | F | F | DEFAULT | | <NULL> | <NULL> |
+--------+------------+---------+-----------+--------------+----------------+-----------+--------+-------+---------+---------------+--------------------------+--------------------------+--------+----------+----------+-------------+-----------+--------------------------+--------------------------+------------+----------+----------+-----------+-----------------------+--------------+---------------+---------+----------+--------------+---------------+------------------+---------+-------------------+----------------+-----------------+---------------+------------+----------------+---------------+----------+----------------+--------+
-- 删除连接6
SQL> DROP SESSIONS 6 ;
SQL> SELECT * FROM SYS_SESSIONS;
+--------+------------+---------+-----------+--------------+----------------+-----------+--------+-------+---------+---------------+--------------------------+--------------------------+--------+----------+----------+-------------+-----------+--------------------------+--------------------------+------------+----------+----------+-----------+-----------------------+--------------+---------------+---------+----------+--------------+---------------+------------------+---------+-------------------+----------------+-----------------+---------------+------------+----------------+---------------+----------+----------------+--------+
| NODEID | SESSION_ID | USER_ID | USER_NAME | CURR_USER_ID | CURR_USER_NAME | SCHEMA_ID | SCHEMA | DB_ID | DB_NAME | IP | START_T | VISIT_T | STATUS | CURR_TID | CURR_CID | AUTO_COMMIT | ISO_LEVEL | TRANS_START_T | CMD_START_T | CURSOR_NUM | MEM_SIZE | CHAR_SET | TIME_ZONE | TIME_FORMAT | LOCK_TIMEOUT | STRICT_COMMIT | RESULT | LANGUAGE | RETURN_ROWID | RETURN_SCHEMA | RETURN_CURSOR_ID | LOB_RET | EMPTY_STR_AS_NULL | OPTIMIZER_MODE | COMPATIBLE_MODE | FILTER_POLICY | TRANS_RDLY | DISABLE_BINLOG | IDENTITY_MODE | APP_NAME | KEYWORD_FILTER | SQL |
+--------+------------+---------+-----------+--------------+----------------+-----------+--------+-------+---------+---------------+--------------------------+--------------------------+--------+----------+----------+-------------+-----------+--------------------------+--------------------------+------------+----------+----------+-----------+-----------------------+--------------+---------------+---------+----------+--------------+---------------+------------------+---------+-------------------+----------------+-----------------+---------------+------------+----------------+---------------+----------+----------------+--------+
| 1 | 5 | 1 | SYSDBA | 1 | SYSDBA | 1 | SYSDBA | 1 | SYSTEM | 192.168.2.236 | 2025-07-11 09:20:00.000 | 2025-07-11 09:29:56.000 | 114 | 1129 | 1 | T | 1 | 2025-07-11 09:29:56.000 | 2025-07-11 09:29:56.000 | 0 | 262144 | UTF8 | GMT+08:00 | YYYY-MM-DD HH24:MI:SS | 0 | F | DEFAULT | PL/SQL | F | F | F | F | F | ALL_ROWS | NONE | 0 | F | F | DEFAULT | | <NULL> | <NULL> |
+--------+------------+---------+-----------+--------------+----------------+-----------+--------+-------+---------+---------------+--------------------------+--------------------------+--------+----------+----------+-------------+-----------+--------------------------+--------------------------+------------+----------+----------+-----------+-----------------------+--------------+---------------+---------+----------+--------------+---------------+------------------+---------+-------------------+----------------+-----------------+---------------+------------+----------------+---------------+----------+----------------+--------+