Mysql validate and find the wrong emails - mysql

Question

Suppose I have a table for user info records, each user may have email, but suppose instead of 'a#gmail.com', system inserted a#gmial.com or a#gmile.com and the same for yahoo, outlook, and hotmail.
But now I should find all the wrong emails, and replace the wrong domain name with correct one.
Something that i have tried before, but not bring the correct result:
select * from users where id not in
(select id form users where
strcmp(email,'#gmail') > 0 OR
strcmp(email,'#yahoo') > 0 OR
strcmp(email,'#hotmail') > 0 OR
strcmp(email,'#outlook') > 0
)

Answer 1

You can use the similar_text() http://php.net/manual/es/function.similar-text.php php function or the levenshtein(), i.e:
$users = //result from select * from users;
foreach($users as $user){
$u = end(explode('#',$user); //store the part of the email after '#'
echo "<br />Gmail:".similar_text($u,"gmail.com",$percent);
echo "<br />Yahoo:".similar_text($u,"yahoo.com",$percent);
echo "<br />Hotmail:".similar_text($u,"hotmail.com",$percent);
echo "<br />outlook:".similar_text($u,"outlook.com",$percent);
}
In this way, you will see the % of similarity between the emails, and then you can set the limit and replace the email for each email provider:
if(similar_text($u,"outlook.com",$percent) > 70){ //If the similarity is up to 70%
$user = substr(0,(str_pos($user,'#')-1))."#outlook.com"; //change the last part of the email for the desired one.
}
This is only a idea, i guess is not the better way to do it...

Answer 2

This would do what you want:
SELECT * FROM `users`
WHERE NOT(email LIKE '%#gmail%'
OR email LIKE '%#hotmail%'
OR email LIKE '%#yahoo%'
OR email LIKE '%#outlook%')
I would also suggest to extend your pattern a bit:
email LIKE '%_#gmail.__%'
This way you check also
There is at least one character before '#'
There is at least a two character domain extension

Answer 3

The obvious way to replace text is the REPLACE() function:
-- Untested
UPDATE users
SET email=REPLACE(email, '#gmile.', '#gmail.')
WHERE email like '%#gmile.%';
Repeat for each string (since it's a one time operation, trying to fit everything into a single query is just not worth the effort.)
In case you wonder, STRCMP(a, b)>0 is basically a convoluted replacement for a>b.

Answer 4

You can use strpos()
select * from users where id not in
(select id form users where
strpos(email,'#gmail') > 0 OR
strpos(email,'#yahoo') > 0 OR
strpos(email,'#hotmail') > 0 OR
strpos(email,'#outlook') > 0
)

Answer 5

Try this using INSTR:
select * from users
where
INSTR(email,'#gmail') +
INSTR(email,'#yahoo') +
INSTR(email,'#hotmail') +
INSTR(email,'#outlook')
= 0;

Answer 6

Did you realize that your nested query has FORM instead of FROM?
Anyway I would suggest you use LIKE instead of STRCMP.