看到一篇文章：在Oracle数据库中使用instr代替like实操(见http://www.linuxidc.com/Linux/2009-12/23599.htm)，看到之后很质疑，以下是我做的简单测试，以对原文作对比验证。

1.创建索引前

SQL> select count(1) from t;

COUNT(1)

----------

11905920

Elapsed: 00:00:11.38

SQL> select count(1) from t where instr(object_name,'A') >0;

COUNT(1)

----------

3947520

Elapsed: 00:00:10.46

SQL> select count(1) from t where object_name like '%A%';

COUNT(1)

----------

3947520

Elapsed: 00:00:12.31

SQL> select count(1) from t where instr(object_name,'A') = 0;

COUNT(1)

----------

7958400

Elapsed: 00:00:10.39

SQL> select count(1) from t where object_name not like '%A%';

COUNT(1)

----------

7958400

Elapsed: 00:00:10.94