How to get ID of the last updated row in MySQL?

Question

How do I get the ID of the last updated row in MySQL using PHP?

Answer 1

I've found an answer to this problem :)

SET @update_id := 0;
UPDATE some_table SET column_name = 'value', id = (SELECT @update_id := id)
WHERE some_other_column = 'blah' LIMIT 1; 
SELECT @update_id;

EDIT by aefxx

This technique can be further expanded to retrieve the ID of every row affected by an update statement:

SET @uids := null;
UPDATE footable
   SET foo = 'bar'
 WHERE fooid > 5
   AND ( SELECT @uids := CONCAT_WS(',', fooid, @uids) );
SELECT @uids;

This will return a string with all the IDs concatenated by a comma.

Answer 2

Hm, I am surprised that among the answers I do not see the easiest solution.

Suppose, item_id is an integer identity column in items table and you update rows with the following statement:

UPDATE items
SET qwe = 'qwe'
WHERE asd = 'asd';

Then, to know the latest affected row right after the statement, you should slightly update the statement into the following:

UPDATE items
SET qwe = 'qwe',
    item_id=LAST_INSERT_ID(item_id)
WHERE asd = 'asd';
SELECT LAST_INSERT_ID();

If you need to update only really changed row, you would need to add a conditional update of the item_id through the LAST_INSERT_ID checking if the data is going to change in the row.

Answer 3

This is officially simple but remarkably counter-intuitive. If you're doing:

update users set status = 'processing' where status = 'pending'
limit 1

Change it to this:

update users set status = 'processing' where status = 'pending'
and last_insert_id(user_id) 
limit 1

The addition of last_insert_id(user_id) in the where clause is telling MySQL to set its internal variable to the ID of the found row. When you pass a value to last_insert_id(expr) like this, it ends up returning that value, which in the case of IDs like here is always a positive integer and therefore always evaluates to true, never interfering with the where clause. This only works if some row was actually found, so remember to check affected rows. You can then get the ID in multiple ways.

MySQL last_insert_id()

You can generate sequences without calling LAST_INSERT_ID(), but the utility of using the function this way is that the ID value is maintained in the server as the last automatically generated value. It is multi-user safe because multiple clients can issue the UPDATE statement and get their own sequence value with the SELECT statement (or mysql_insert_id()), without affecting or being affected by other clients that generate their own sequence values.

MySQL mysql_insert_id()

Returns the value generated for an AUTO_INCREMENT column by the previous INSERT or UPDATE statement. Use this function after you have performed an INSERT statement into a table that contains an AUTO_INCREMENT field, or have used INSERT or UPDATE to set a column value with LAST_INSERT_ID(expr).

The reason for the differences between LAST_INSERT_ID() and mysql_insert_id() is that LAST_INSERT_ID() is made easy to use in scripts while mysql_insert_id() tries to provide more exact information about what happens to the AUTO_INCREMENT column.

PHP mysqli_insert_id()

Performing an INSERT or UPDATE statement using the LAST_INSERT_ID() function will also modify the value returned by the mysqli_insert_id() function.

Putting it all together:

$affected_rows = DB::getAffectedRows("
    update users set status = 'processing' 
    where status = 'pending' and last_insert_id(user_id) 
    limit 1"
);
if ($affected_rows) {
    $user_id = DB::getInsertId();
}

(FYI that DB class is here.)

Answer 4

This is the same method as Salman A's answer, but here's the code you actually need to do it.

First, edit your table so that it will automatically keep track of whenever a row is modified. Remove the last line if you only want to know when a row was initially inserted.

ALTER TABLE mytable
ADD lastmodified TIMESTAMP 
    DEFAULT CURRENT_TIMESTAMP 
    ON UPDATE CURRENT_TIMESTAMP;

Then, to find out the last updated row, you can use this code.

SELECT id FROM mytable ORDER BY lastmodified DESC LIMIT 1;

This code is all lifted from MySQL vs PostgreSQL: Adding a 'Last Modified Time' Column to a Table and MySQL Manual: Sorting Rows. I just assembled it.

Answer 5

Query :

$sqlQuery = "UPDATE 
            update_table 
        SET 
            set_name = 'value' 
        WHERE 
            where_name = 'name'
        LIMIT 1;";

PHP function:

function updateAndGetId($sqlQuery)
{
    mysql_query(str_replace("SET", "SET id = LAST_INSERT_ID(id),", $sqlQuery));
    return mysql_insert_id();
}

It's work for me ;)

Answer 6

SET @uids := "";
UPDATE myf___ingtable
   SET id = id
   WHERE id < 5
  AND ( SELECT @uids := CONCAT_WS(',', CAST(id AS CHAR CHARACTER SET utf8), @uids) );
SELECT @uids;

I had to CAST the id (dunno why)... or I cannot get the @uids content (it was a blob) Btw many thanks for Pomyk answer!

Answer 7

ID of the last updated row is the same ID that you use in the 'updateQuery' to found & update that row. So, just save(call) that ID on anyway you want.

last_insert_id() depends of the AUTO_INCREMENT, but the last updated ID not.

Answer 8

Hey, I just needed such a trick - I solved it in a different way, maybe it'll work for you. Note this is not a scalable solution and will be very bad for large data sets.

Split your query into two parts -

first, select the ids of the rows you want to update and store them in a temporary table.

secondly, do the original update with the condition in the update statement changed to where id in temp_table.

And to ensure concurrency, you need to lock the table before this two steps and then release the lock at the end.

Again, this works for me, for a query which ends with limit 1, so I don't even use a temp table, but instead simply a variable to store the result of the first select.

I prefer this method since I know I will always update only one row, and the code is straightforward.

Answer 9

My solution is , first decide the "id" ( @uids ) with select command and after update this id with @uids .

SET @uids := (SELECT id FROM table WHERE some = 0 LIMIT 1);
UPDATE table SET col = 1 WHERE id = @uids;SELECT @uids;

it worked on my project.

Answer 10

Further more to the Above Accepted Answer
For those who were wondering about := & =

Significant difference between := and =, and that is that := works as a variable-assignment operator everywhere, while = only works that way in SET statements, and is a comparison operator everywhere else.

So SELECT @var = 1 + 1; will leave @var unchanged and return a boolean (1 or 0 depending on the current value of @var), while SELECT @var := 1 + 1; will change @var to 2, and return 2. [Source]

Answer 11

If you are only doing insertions, and want one from the same session, do as per peirix's answer. If you are doing modifications, you will need to modify your database schema to store which entry was most recently updated.

If you want the id from the last modification, which may have been from a different session (i.e. not the one that was just done by the PHP code running at present, but one done in response to a different request), you can add a TIMESTAMP column to your table called last_modified (see http://dev.mysql.com/doc/refman/5.1/en/datetime.html for information), and then when you update, set last_modified=CURRENT_TIME.

Having set this, you can then use a query like: SELECT id FROM table ORDER BY last_modified DESC LIMIT 1; to get the most recently modified row.

Answer 12

No need for so long Mysql code. In PHP, query should look something like this:

$updateQuery = mysql_query("UPDATE table_name SET row='value' WHERE id='$id'") or die ('Error');
$lastUpdatedId = mysql_insert_id();