As MySQL doesn’t have inherent support for updating more than one rows or records with a single update query as it does for insert query, in a situation which needs us to perform updating to tens of thousands or even millions of records, one update query for each row seems to be too much.
Reducing the number of SQL database queries is the top tip for optimizing SQL applications.
So, is there any other way around with just a few MySQL queries that equals to millions of single row update queries?
Yes, but you need a temporary table.
Step 1: Create a temporary table
This table should have 2 columns: 1) an ID column that references the original record’s primary key in the original table, 2) the column containing the new value to be updated with.
Creating this table, you can use insert queries as it conveniently inserts more than one rows at a time (with a single query) — actually, as many rows as you need, like 1000 a time.
Step 2: Transfer the new values from the temporary table to the intended table
Use the query below:
UPDATE original_table, temp_table SET original_table.update_column = temp_table.update_column WHERE original_table.id = temp_table.original_idTo transfer all the new values you have in the temporary table to the original table. After this, you have successfully updated the original table with much much less than a million queries, probably just a hundred or so.
UPDATE =============================================
So here’s perhaps a better idea in most of the cases, use the CASE WHEN ELSE END syntax of MySQL to update multiple rows in the options table of your web application:
UPDATE `options` SET `value` = CASE `name`
WHEN 'site_name' THEN 'My Blog'
WHEN 'site_url' THEN 'http://www.example.com'
WHEN 'site_email' THEN '[email protected]'
ELSE `value`
ENDMake sure you include the ELSE `value` because if you don’t, the other rows not mentioned here will be updated to have empty values.
Update multiple records in a table by `ID` =============================================
Below is an example of updating more than one rows in a table by the id field. The field_name field is updated to the corresponding value: value_1, value_2, or value_3 if the id equals to 1, 2, or 3:
UPDATE `table_name` SET `field_name` = CASE `id`
WHEN '1' THEN 'value_1'
WHEN '2' THEN 'value_2'
WHEN '3' THEN 'value_3'
ELSE `field_name`
ENDYet another way =============================================
There’s also another way of doing this: https://www.kavoir.com/2009/05/mysql-insert-if-doesnt-exist-otherwise-update-the-existing-row.html
If all the record that want to be updated is the same, just
UPDATE myTable SET type=”A”, model=”B” WHERE id IN ( 1, 2, 3)
Nice!
hello i want to ask if how can i able to update one single row in different tables. i use php and mysql as my repository
Excellent! Took me long to find this, have been pulling my hair out for days until I found this! Thank you!
Excellent Tip! It seems really simple now that I see it, but I have been using a lot of slow loops for a long time. Thanks.
we have been fighting the slow sql update problem for days now,
your solution was quick to implement and works like a charm.
thanks!!!!
I am using MySQL 5.0. Do the databases need to be of a certain type (MyISAM, InnoDB) for this to work?
I think either type is fine with this approach.
no one is better user oracle 10i
Sorry I’m a bit lost here – is your update method using CASE part of the original method (eg: creating a temporary table, inserting first) or is that a way to avoid a temporary table all together? Could you please provide the structure of the options table? Thanks a lot, I would appreciate it.
Thanks for the info.
Can we write a single MySQL query to update multiple ID’s inside the same table?
The SQL is added at the end of the article.
Have you benchmarked the CASE statement to see if it is actually better than the temporary table solution?
I’d also be interested in how both solutions compare to just doing an INSERT ON DUPLICATE KEY UPDATE.
As an alternative to an ELSE value, you can provide a WHERE clause:
UPDATE `table` SET `col` = CASE `id`
WHEN 1 THEN ‘one’
WHEN 2 THEN ‘two’
WHEN 3 THEN ‘three’
END
WHERE `id` IN (1, 2, 3)
Same result but without doing a no-op update no rows you don’t care about.
I used
UPDATE `table_name` SET `field_name` = CASE `id`
WHEN ‘1’ THEN ‘value_1’
WHEN ‘2’ THEN ‘value_2’
WHEN ‘3’ THEN ‘value_3’
ELSE `field_name`
END
I am thrilled! Thanks a lot!!
Here’s a much more efficient MySQL-flavored solution:
INSERT INTO tbl_name
(pk_cols, update_cols)
VALUES
(pk_vals, update_vals),
…
(pk_vals, update_vals)
ON DUPLICATE KEY UPDATE
update_col=VALUES(update_col),
…
update_col=VALUES(update_col);
OPTIMIZE TABLE tbl_name;
Example as per article:
INSERT INTO categories
(id, display_order, title)
VALUES
(1, 3, ‘New Title 1’),
(2, 4, ‘New Title 2’),
(3, 5, ‘New Title 3’)
ON DUPLICATE KEY UPDATE
display_order=VALUES(display_order),
title=VALUES(title);
OPTIMIZE TABLE tbl_name;
The advantage of this solution is that it’s driven by the indexing of the primary keys, on which a CASE cannot rely. The OPTIMIZE TABLE part is only advantageous when updating variable-length cells (i.e. VARCHAR, VARBINARY, BLOB, or TEXT). For multiple-column primary keys, you simply specify all of them in the statement.
Hello dear friends.
I want to update multiple rows on my table using php, but I have this error:
Notice: Undefined offset: 7 in C:\Program Files\EasyPHP-5.3.9\www\ajane\admin\creacomok.php on line 198
That’is my code :
…
$designationm = array();
$datelivm = array();
$etatm = array();
$qtem = array();
foreach ($_POST[‘designationm’] as $desim => $dm) { array_push ($designationm, $dm); }
foreach ($_POST[‘datelivm’] as $datlm => $dlm) { array_push ($datelivm, $dlm); }
foreach ($_POST[‘etatm’] as $etm => $etam) { array_push ($etatm, $etam); }
foreach ($_POST[‘qtem’] as $qm => $qtm) { array_push ($qtem, $qtm); }
include’conecdb.php’;
$sql3=”SELECT * FROM commande”;
$result3=mysql_query($sql3);
$count=mysql_num_rows($result3);
for($i=1;$i<$count;$i++) {
$sql1='UPDATE commande SET designation="'.$designationm[$i].'", dateliv="'.$datelivm[$i].'", etat="'.$etatm[$i].'", qte="'.$qtem[$i].'" WHERE numcli="'.$numcli.'"';
$result1=mysql_query($sql1);
}
…
I tried using:
UPDATE `table` SET `col` = CASE `id`
WHEN 1 THEN ‘one’
WHEN 2 THEN ‘two’
WHEN 3 THEN ‘three’
END
WHERE `id` IN (1, 2, 3)
but performance was very similar to doing individual updates.
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GOOD IDEA THANKS