MySQL conditionally UPDATE rows' boolean column values based on a whitelist of ids

I'm trying to update a set of records (boolean fields) in a single query if possible.

The input is coming from paginated radio controls, so a given POST will have the page's worth of IDs with a true or false value.

I was trying to go this direction:

UPDATE my_table
    SET field = CASE
        WHEN id IN (/* true ids */) THEN TRUE
        WHEN id IN (/* false ids */) THEN FALSE
    END

But this resulted in the "true id" rows being updated to true, and ALL other rows were updated to false.

I assume I've made some gross syntactical error, o开发者_JAVA技巧r perhaps that I'm approaching this incorrectly.

Any thoughts on a solution?

Didn't you forget to do an "ELSE" in the case statement?

UPDATE my_table
    SET field = CASE
        WHEN id IN (/* true ids */) THEN TRUE
        WHEN id IN (/* false ids */) THEN FALSE
        ELSE field=field 
    END

Without the ELSE, I assume the evaluation chain stops at the last WHEN and executes that update. Also, you are not limiting the rows that you are trying to update; if you don't do the ELSE you should at least tell the update to only update the rows you want and not all the rows (as you are doing). Look at the WHERE clause below:

  UPDATE my_table
        SET field = CASE
            WHEN id IN (/* true ids */) THEN TRUE
            WHEN id IN (/* false ids */) THEN FALSE
        END
  WHERE id in (true ids + false_ids)

You can avoid field = field

update my_table
    set field = case
        when id in (....) then true
        when id in (...) then false
        else field
    end

You can avoid the use of a case block for this task because you are setting a conditional boolean value.

Declare all ids that should be changed in the WHERE clause.

Declare all of the true id values in the SET clause's IN() condition. If any given id is found in the IN then the boolean value will become true, else false.

Demo

TABLE `my_table` (
  `id` int(10) UNSIGNED NOT NULL,
  `my_boolean` boolean
) ENGINE=MyISAM DEFAULT CHARSET=latin1;
ALTER TABLE `my_table`
  ADD PRIMARY KEY (`id`);
  
INSERT INTO `my_table` VALUES
(1,true),
(2,false),
(3,true),
(4,false),
(5,true),
(6,false);

UPDATE my_table
SET my_boolean = (id IN (2,4))
WHERE id IN (2,3);

SELECT * FROM my_table;

Output:

id  my_boolean
1   true
2   true       #changed
3   false      #changed
4   false
5   true
6   false