Query two tables where one row is like another - mysql

Question

I have two table queries.
The first table looks like:
| id | Number |
+--------+-------------+
| 1 | WDX |
| 2 | ABd32 |
| 3 | CACY |
and second like:
| id | realNumber |
+--------+-------------+
| 1 | w_WDX_zed |
| 2 | ABd32_ala |
| 3 | guava |
The output needs to looks like:
| id | output |
+--------+-------------+
| 1 | w_WDX_zed |
| 2 | ABd32_ala |
| 3 | CACY |
In the first table there are car plates, and in second there are plates_username. I need to connect them and update first table to match.
I was trying to do this like:
UPDATE `TAB_a` a, `TAB_b` b
SET a.`Number` = b.`realNumber`
WHERE a.`Number` LIKE CONCAT('%',b.`realNumber`,'%') AND a.Number <> b.`realNumber`;
But that does not work.

Answer 1

update plates p
inner join plate_users pu
on pu.realNumber like concat(concat('%', p.number), '%')
set p.number = pu.number
This is, however, fraught with danger -- if there are plates that are substrings of another plate you're likely to get unwanted results.
if realNumber is supposed to be , how come the first one is _? If those type weren't in there, it would be a lot easier and safer.
EDIT
Ok, after a little more info below, here are two more options you can try:
update plates p
inner join plate_users pu
on pu.number like concat('%\_', p.number)
or pu.number like concat(p.number, '\_%')
or pu.number like concat(concat('%\_', p.number), '\_%')
set p.number = pu.number
Fiddle: http://sqlfiddle.com/#!9/e8999/1
and
update plates p
inner join plate_users pu
on pu.number REGEXP concat(concat('.*_?', p.number), '_?.*')
set p.number = pu.number
Fiddle: http://sqlfiddle.com/#!9/c5bc7/1
All of the above give the desired results on your minimal dataset, but i strongly suggest backing up your data before you run any of these on your live data.
The last two options are preferable, because they require at least one underscore in the realNumber.