Best way to update/translate the values of a field mysql - mysql

Question

So, I need to update/translate a field called status_id on my mysql table, basically following this:
WHERE | SHOULD BE
0 | 0
1 | 1
2 | 4
3 | 8
4 | 9
5 | 10
6 | 6
7 | 2
8 | 11
I've though of a few methods, but i'm not sure which one would be the best
The first one:
Use some transition elements, in this case, the desired final value+100
UPDATE myTable
SET status_id = 100
WHERE status_id = 0;
-- ...
UPDATE myTable
SET status_id = 111
WHERE status_id = 8;
-- ...
UPDATE myTable
SET status_id = 0
WHERE status_id = 100;
-- ...
UPDATE myTable
SET status_id = 11
WHERE status_id = 111;
The second one:
use CASE
UPDATE myTable SET status_id =
CASE
WHEN status_id = 0 THEN 0
-- ...
WHEN status_id = 8 THEN 11
ELSE status_id
END
This will only be done once, i just want to make sure i do not mess this up (I have backups, but it's always good to not need them)

Answer 1

For MySql 8.0+ you can create a CTE that returns each pair of current and new status_id and join it to the table in the UPDATE statement:
WITH cte(status_id, new_status_id) AS (VALUES
ROW(0, 0),
ROW(1, 1),
ROW(2, 4),
ROW(3, 8),
ROW(4, 9),
ROW(5, 10),
ROW(6, 6),
ROW(7, 2),
ROW(8, 11)
)
UPDATE myTable t
INNER JOIN cte c ON c.status_id = t.status_id
SET t.status_id = c.new_status_id
See the demo.
For prior versions join a subquery to the table:
UPDATE myTable t
INNER JOIN (
SELECT 0 status_id, 0 new_status_id UNION ALL
SELECT 1, 1 UNION ALL
SELECT 2, 4 UNION ALL
SELECT 3, 8 UNION ALL
SELECT 4, 9 UNION ALL
SELECT 5, 10 UNION ALL
SELECT 6, 6 UNION ALL
SELECT 7, 2 UNION ALL
SELECT 8, 11
) c ON c.status_id = t.status_id
SET t.status_id = c.new_status_id
See the demo.
Note that I don't see any reason to keep where both values are equal, but MySql will not perform update in such a case.

Answer 2

If you want to have some extra fun, you can use MySQL's JSON capabilities:
UPDATE myTable SET status_id = JSON_EXTRACT(
CAST('
{
"0": 0,
"1": 1,
"2": 4,
"3": 8,
"4": 9,
"5": 10,
"6": 6,
"7": 2,
"8": 11
}'
AS JSON
),
CONCAT('$."', status_id, '"')
)
It can actually be more convenient to write and maintain (and in some cases also cleaner and simpler to construct automatically in code).

Answer 3

You can put your values in a "holder table".
CREATE TEMPORARY TABLE my_temp_table (before_value int, after_value int) ENGINE=MEMORY;
/* populate your my_temp_table with your cross-walk values */
INSERT INTO my_temp_table (before_value, after_value)
SELECT 101, 201 FROM DUAL
UNION ALL SELECT 102, 202 FROM DUAL;
(etc, etc, i'm giving example values, put in your own real values.)
Update myTable
Set status_id = my_temp_table.after_value
from myTable , my_temp_table
Where
myTable.status_id = my_temp_table.before_value
That means you have "matches" that are not ambiguous.
The above is (one) "set based" approach.
If you have to do it sequentially (aka, you can't do the second update until the first update has been completed), you have to update one by one (also known as Row by Agonizing Row) RBAR.
REFERENCE:
https://dev.mysql.com/doc/refman/8.0/en/create-temporary-table.html

Answer 4

UPDATE myTable
SET status_id = FIND_IN_SET(status_id, '1,7,x,2,x,6,x,3,4,5,8')
WHERE status_id BETWEEN 0 AND 8;
https://dbfiddle.uk/?rdbms=mysql_8.0&fiddle=5dd617361fcf6a3d2d669625dc809db1
PS. This is a special case which allows such special solution.