单个查询中的多个mysql更新

Question

i have a table named member_photos that stores member_id , photo_id , photo_dir and photo_name , when someone edited his photos, it posts an array containts info about photos, posted page has an array with photo informations but my problem is i use foreach loop and update every photo one by one like

 UPDATE member_photos 
    SET photo_name = '$newphotoname' 
  WHERE photo_id = '$photoid'

that works but when this guy has 20 photos, array has 20 items so loop will do 20 queries. Is there any way that i can update all photos with single query?

Answer 1

UPDATE categories
SET display_order = CASE id
    WHEN 1 THEN 3
    WHEN 2 THEN 4
    WHEN 3 THEN 5
END,
title = CASE id
    WHEN 1 THEN 'New Title 1'
    WHEN 2 THEN 'New Title 2'
    WHEN 3 THEN 'New Title 3'
END
WHERE id IN (1,2,3)

in PHP

// An array containing the category ids as keys and the new positions as values
$display_order = array(
    1 => 4,
    2 => 1,
    3 => 2,
    4 => 3,
    5 => 9,
    6 => 5,
    7 => 8,
    8 => 9
);

$ids = implode(',', array_keys($display_order));
$sql = "UPDATE categories SET display_order = CASE id ";
foreach ($display_order as $id => $ordinal) {
    $sql .= sprintf("WHEN %d THEN %d ", $id, $ordinal);
}
$sql .= "END WHERE id IN ($ids)";
echo $sql;

the resource for this info: http://www.karlrixon.co.uk/writing/update-multiple-rows-with-different-values-and-a-single-sql-query/