No Changed Rows Produced by this mySQL update query. Why?
+--------+-----------------------+
| id     | email                 |
+--------+-----------------------+
| 142755 | xxxxxxx@xxxxxxxxx.com |
+--------+-----------------------+

+--------+------------------------+
| person | email                  |
+--------+------------------------+
|     0  | xxxxxxx@xxxxxxxxx.com  |
+--------+------------------------+

UPDATE
person, no_dma
SET no_dma.person = person.id
WHERE person.email = no_dma.email;

Query OK, 0 rows affected (9.31 sec)
Rows matched: 0  Changed: 0  Warnings: 0

mysql> select person, email from no_dma limit 0,1;
+--------+------------------------+
| person | email                  |
+--------+------------------------+
 |     0 | tom_r1989@xxxxxxx.com
+--------+------------------------+
1 row in set (0.00 sec)

mysql> select email from no_dma where email = 'tom_r1989@xxxxxxx.com';
Empty set (0.00 sec)

mysql> select email from no_dma where TRIM(email) = 'tom_r1989@xxxxxxx.com';
Empty set (0.46 sec)

mysql> SELECT CONCAT('"',email,'"') from no_dma limit 0,3;
+-----------------------+
| CONCAT('"',email,'"') |
+-----------------------+
"  |amjor308@xxx.com
"   |utt@xxx.com
"  |00000000@xxx.com
+-----------------------+


mysql> SELECT email from no_dma limit 0,3;
+--------------------+
| email              |
+--------------------+
 |+amjor308@xxx.com
  |mutt@xxx.com
 |000000000@xxx.com
+--------------------+

mysql> SELECT TRIM(email) from no_dma limit 0,3;
+--------------------+
| TRIM(email)        |
+--------------------+
 |+amjor308@aol.com
  |mutt@excite.com
 |000000000@aol.com
+--------------------+
3 rows in set (0.00 sec)