Update multiple rows with known keys without inserting new rows if nonexistent keys are found

Question

Hello,

Let's imagine that we have table items...

table: items
item_id INT PRIMARY AUTO_INCREMENT
title VARCHAR(255)
views INT

Let's imagine that it is filled with something like

(1, item-1, 10),
(2, item-2, 10),
(3, item-3, 15)

I want to make multi update view for this items from data taken from this array [item_id] => [views]

'1' => '50',
'2' => '60',
'3' => '70',
'5' => '10'

IMPORTANT! Please note that we have item_id=5 in array, but we don't have item_id=5 in database.

I can use INSERT ... ON DUPLICATE KEY UPDATE, but this way image_id=5 will be inserted into talbe items. How to avoid inserting new key? I just want item_id=5 be skipped because it is not in table.

Of course, before execution I can select existing keys from items table; then compare with keys in array; delete nonexistent keys and perform INSERT ... ON DUPLICATE KEY UPDATE. But maybe there is some more elegant solutions?

Thank you.

Answer 1

You may try to generate a table of literals and update items by joining with the table:

UPDATE items
    JOIN (SELECT 1 as item_id, 50 as views
          UNION ALL
          SELECT 2 as item_id, 60 as views
          UNION ALL
          SELECT 3 as item_id, 70 as views
          UNION ALL
          SELECT 5 as item_id, 10 as views
          ) as updates
         USING(item_id)
 SET items.views = updates.views;