mysql sequence swapping values - mysql

Question

Database table
id serial account speeddialsort dest
107 155 501 1 020341542
115 155 501 2 004407152222
116 155 501 3 00951242454
117 155 501 4 0794245544
118 266 700 1 004465652212
119 266 700 2 0044845482
Data presented to user
This a list of account's 501 speed dial slots.
I can send the speeddialsort and dest if required from a form, what sql method can I then use to manage user editing of the speed dial order.
The order is to be moved up or down
speeddialsort dest
#1 020341542
#2 004407152222
#3 00951242454
#4 0794245544
For example user selects speed dial #3 be moved up. The speeddialsort of #2 and #3 will need to be swapped

Answer 1

I asume speeddialsort is UNIQUE and dest isn't?
Asume $int_short to be supplied sort_id and $int_previous_sort to be the value is was before:
INSERT INTO table (speeddialsort, dest)
SELECT speeddialsort, dest
FROM (SELECT {$int_sort} AS speeddialsort, dest
FROM table
WHERE speeddialsort = {$int_previous_sort}
UNION ALL
SELECT {$int_previous_sort}, dest
FROM table
WHERE speeddialsort = {$int_sort})
ON DUPLICATE KEY UPDATE dest = VALUES(dest)
In case both are UNIQUE, it'd be easier to simply remove and readd them. That, or:
INSERT INTO table (speeddialsort, dest)
SELECT speeddialsort, dest
FROM (SELECT {$int_sort} AS speeddialsort, NULL AS dest
UNION ALL
SELECT {$int_previous_sort}, NULL
UNION ALL
SELECT {$int_sort}, dest
FROM table
WHERE speeddialsort = {$int_previous_sort}
UNION ALL
SELECT {$int_previous_sort}, dest
FROM table
WHERE speeddialsort = {$int_sort})
ON DUPLICATE KEY UPDATE dest = VALUES(dest)
Should work aswell.

Answer 2

Move Up:
UPDATE my_table AS t1 SET t1.dest =
IFNULL( ( SELECT t2.dest FROM my_table AS t2
WHERE t2.speeddialsort IN( {$i}, {$i-1} ) AND
t2.account = $account AND t2.dest <> t1.dest ), t1.dest )
WHERE t1.speeddialsort IN( {$i}, {$i-1} ) AND t1.account = {$account}
to Move Down just replace $i-1s with $i+1
($i is the speeddialsort you want to move, $account is the account id)

Answer 3

I create a table and the row serial is made in a continuous sequence by using
mysql user defined variable.
ID serial
101 1
103 2
104 3
110 4
In this to move the item with serial 4 to 2
SET #a = 2;
UPDATE tableName SET serial = #a:=#a + 1 WHERE serial >= 2 AND serial < 4
ORDER BY serial DESC;
UPDATE tableName SET serial = 2 WHERE ID = 1;
This query will add 1 to all the serial values less than 4 and greater than 2 and then update the row with serial 4 with value 2.
And to move item 2 to 4
SET #b = 4;
UPDATE tableName SET ord = #b:=#b - 1 WHERE serial > 2 AND serial < (4 + 1)
ORDER BY serial DESC;
UPDATE tableName SET serial = 4 WHERE ID = 1 ;
I am not talking about Auto Increment.In my case I need to order the values as user required.So i cannot use Auto increment.