刚刚开始接触Oracle，使用的工具是Sql Developer。在看执行计划的的时候，选中SQL语句，直接F5即可。
但是这里的执行计划不是最终的执行计划，它使用的是 explain for 命令。
这里介绍个可查看真正执行计划的工具， autotrace ，下面是用法示例：
SQL> set autotrace Usage: SET AUTOT[RACE] {OFF | ON | TRACE[ONLY]} [EXP[LAIN]] [STAT[ISTICS]] SQL> set autot on SQL> set timing on SQL> select * from dual; D - X Elapsed: 00:00:00.00 Execution Plan ---------------------------------------------------------- Plan hash value: 272002086 -------------------------------------------------------------------------- | Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | -------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | 1 | 2 | 2 (0)| 00:00:01 | | 1 | TABLE ACCESS FULL| DUAL | 1 | 2 | 2 (0)| 00:00:01 | -------------------------------------------------------------------------- Statistics ---------------------------------------------------------- 1 recursive calls 0 db block gets 2 consistent gets 0 physical reads 0 redo size 522 bytes sent via SQL*Net to client 519 bytes received via SQL*Net from client 2 SQL*Net roundtrips to/from client 0 sorts (memory) 0 sorts (disk) 1 rows processed SQL>