how to search in text ?(怎么避免在TEXT字段中大小写的混合查找？)

[zhou haiping]

Example:
mysql> select * from testabc;
+------+------+------+-------+-------+
| f1 | f2 | f3 | stext | sblob |
+------+------+------+-------+-------+
| 1 | abc | abc | abc | NULL |
| 1 | ABC | ABC | aBC | NULL |
| 1 | Abc | Abc | NULL | NULL |
+------+------+------+-------+-------+
3 rows in set (0.05 sec)

mysql> select * from testabc where stext like '%b%';
+------+------+------+-------+-------+
| f1 | f2 | f3 | stext | sblob |
+------+------+------+-------+-------+
| 1 | abc | abc | abc | NULL |
| 1 | ABC | ABC | aBC | NULL |
+------+------+------+-------+-------+
2 rows in set (0.01 sec)

why the result is 2 rows with "abc" and "aBC"?

why the result not is "abc"?

How do I resolve the problem( only 1 row)?/(怎么让他只显示一行啊？或者说区分大小写？)