select increment counter reset by user in mysql - mysql

Question

I read about create variable for increment in select in this post select increment counter in mysql
I need some addition to this query.. I need to reset the increment based on user_id.
Sample data :
id user_id name
1 1 A
2 2 B
3 3 C
4 1 D
5 2 E
6 2 F
7 1 G
8 3 H
Expected result:
id user_id name increment
1 1 A 1
4 1 D 2
7 1 G 3
2 2 B 1
5 2 E 2
6 2 F 3
3 3 C 1
8 3 H 2
It's not stop only until 3 increments, if I have more row with user_id, it will continue the increment.
How do I make query so the output look like that? Thanks!

Answer 1

Try this:
SELECT A.*, CASE WHEN id=user_id THEN 1
WHEN id>user_id THEN 2
ELSE 0 END increment
FROM yourTable A
ORDER BY A.user_id;
See it run on SQL Fiddle.

Answer 2

You do not need a variable to do that. simple COUNT(), and GROUP BY would do the trick.
SELECT user_id, name, COUNT(user_id) AS increment FROM your_table GROUP BY user_id;
But this will return a single value for one user.
This will pass all count.
SELECT user_id, name, (SELECT COUNT(t2.user_id) FROM your_table t2 WHERE t2.user_id=t1.user_id) AS increment FROM your_table t1;
I'm not a expert at larevel. This is a simple PHP code.
<?php
$db = new mysqli("localhost","root","","test");
$sql = $db->query("SELECT * FROM your_table ORDER BY user_id");
$name_array = array();
$array_counts = array();
?>
<table>
<tr>
<th>id</th>
<th>user id</th>
<th>name</th>
<th>increment</th>
</tr>
<?php
while ($row = $sql->fetch_assoc()){
if (in_array($row['user_id'],$name_array)){
$array_counts[$row['user_id']][0] = $array_counts[$row['user_id']][0]+1;
} else {
$array_counts[$row['user_id']][0] = 1;
}
array_push($name_array,$row['user_id']);
?>
<tr>
<td><?php echo $row['id']; ?></td>
<td><?php echo $row['user_id']; ?></td>
<td><?php echo $row['name']; ?></td>
<td><?php echo $array_counts[$row['user_id']][0]; ?></td>
</tr>
<?php
}
?>
</table>

Answer 3

I was looking for something similar and I may have worked it out (maybe it wasn't exactly what you were looking for) :
SET #increment := 0;
SET #user_id_mem := 0;
SELECT
#increment := CASE WHEN tbl.user_id = #user_id_mem THEN (#increment+1) ELSE 1 END as increment,
tbl.id,
#user_id_mem := tbl.user_id,
tbl.name
FROM YOURTABLE tbl
ORDER BY user_id;