大小写转换函数

1、将字母转换为大写：

upper();

ucase();

2、将字母转换为小写：

lower();

lcase();

mysql> select upper("mysql"),ucase("mYsql"),lower("MYSQL"),lcase("MySQL");
+----------------+----------------+----------------+----------------+
| upper("mysql") | ucase("mYsql") | lower("MYSQL") | lcase("MySQL") |
+----------------+----------------+----------------+----------------+
| MYSQL          | MYSQL          | mysql          | mysql          |
+----------------+----------------+----------------+----------------+
1 row in set (0.00 sec)

mysql> select upper("--");
+-------------+
| upper("--") |
+-------------+
| --          |
+-------------+
1 row in set (0.00 sec)

mysql> select upper("--mysql");
+------------------+
| upper("--mysql") |
+------------------+
| --MYSQL          |
+------------------+
1 row in set (0.00 sec)

mysql> select upper('--my数据库');
+------------------------+
| upper('--my数据库')    |
+------------------------+
| --MY数据库             |
+------------------------+
1 row in set (0.00 sec)