mysql> CREATE TABLE chartest (
    ->   charval1 CHAR(10) NOT NULL,
    ->   charval2 CHAR(10) NOT NULL,
    ->   varcharval VARCHAR(30) NOT NULL
    -> );
Query OK, 0 rows affected (0.03 sec)
 
mysql> INSERT INTO chartest VALUES ('aaa','aaa','aaa');
Query OK, 1 row affected (0.02 sec)
 
mysql> INSERT INTO chartest
    ->   VALUES ('aaaaaa      ','aaa','aaa'); -- should truncate to 'aaaaaa    '
Query OK, 1 row affected (0.02 sec)
 
mysql> INSERT INTO chartest
    ->   VALUES ('aaaaaaaaaaaa','aaa','aaa'); -- should throw error
Query OK, 1 row affected (0.00 sec)
 
mysql> SELECT * FROM chartest; -- should show two rows
+------------+----------+------------+
| charval1   | charval2 | varcharval |
+------------+----------+------------+
| aaa        | aaa      | aaa        |
| aaaaaa     | aaa      | aaa        |
| aaaaaaaaaa | aaa      | aaa        |
+------------+----------+------------+
3 rows in set (0.02 sec)
 
mysql> DELETE FROM chartest WHERE charval1='aaaaaa';
Query OK, 1 row affected (0.01 sec)
 
mysql> SELECT * FROM chartest; -- shoud show one row
+------------+----------+------------+
| charval1   | charval2 | varcharval |
+------------+----------+------------+
| aaa        | aaa      | aaa        |
| aaaaaaaaaa | aaa      | aaa        |
+------------+----------+------------+
2 rows in set (0.00 sec)
 
mysql> SELECT * FROM chartest WHERE charval1=varcharval;
+----------+----------+------------+
| charval1 | charval2 | varcharval |
+----------+----------+------------+
| aaa      | aaa      | aaa        |
+----------+----------+------------+
1 row in set (0.00 sec)
 
mysql> SELECT CONCAT(charval1,'X') AS res FROM chartest;
+-------------+
| res         |
+-------------+
| aaaX        |
| aaaaaaaaaaX |
+-------------+
2 rows in set (0.00 sec)
 
mysql> SELECT CHAR_LENGTH(CONCAT(charval1,charval2)) AS res FROM chartest;
+-----+
| res |
+-----+
|   6 |
|  13 |
+-----+
2 rows in set (0.01 sec)
 
mysql> SELECT CHAR_LENGTH(charval1) + CHAR_LENGTH(charval2)
    ->   AS res
    ->   FROM chartest;
+-----+
| res |
+-----+
|   6 |
|  13 |
+-----+
2 rows in set (0.00 sec)