--'开头和结尾都是 % ,对不起，很难优化'

sys@mescp> select * from test_like where object_name like '%%';


Execution Plan

----------------------------------------------------------

0 SELECT STATEMENT Optimizer=CHOOSE (Cost=6 Card=655 Bytes=15720)

1 0 TABLE ACCESS (FULL) OF 'TEST_LIKE' (Cost=6 Card=655 ytes=15720)

　　-- '以常量结束，直接写的时候是不能应用index的'

sys@mescp> select * from test_like where object_name like '%S';

Execution Plan

----------------------------------------------------------

0 SELECT STATEMENT Optimizer=CHOOSE (Cost=6 Card=655 Bytes=15720)

1 0 TABLE ACCESS (FULL) OF 'TEST_LIKE' (Cost=6 Card=655 Bytes=15720)

　　--'以常量结束的，加个reverse 函数，又可以用上index了'

sys@mescp> select * from test_like where reverse(object_name)like reverse('%AS');

Execution Plan

----------------------------------------------------------

0 SELECT STATEMENT Optimizer=CHOOSE (Cost=2 Card=655 Bytes=15720)

1 0 TABLE ACCESS (BY INDEX ROWID) OF 'TEST_LIKE' (Cost=2 Card=655 Bytes=15720)

2 1 INDEX (RANGE SCAN) OF 'TEST_LIKE__NAME_REVERSE' (NON-UNIQUE) (Cost=2 Card=118)