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Get the ID generated from the previous INSERT operation
(PHP 4, PHP 5, PECL mysql:1.0)
Example 1447. mysql_insert_id() example<?phpCode Examples / Notes » mysql_insert_idvksgeneric
You can't do an INSERT DELAYED and expect to get anything but zero, for it runs in a separate thread, and mysql_insert_id() is tied to the current thread. Vlad mariano
When used in transactions, mysql_insert_id() MUST be called before committing. Otherwise, it will return unpredictable results.
daiguo
To: Ben AT alfreido.com <?php function previous_id($table, $id_column) { if ($table && $id_column) { $result = mysql_query("SELECT MAX(".$id_column.") AS maxid FROM ".$table); $stuff = mysql_fetch_assoc($result); return $stuff['maxid']; } else { return false; } } ?> Use MySQL's built-in function MAX(). It's faster because any min/max algorithm is faster than sorting entire table. sly
To get the NEXT insert id use the mysql query SHOW TABLE STATUS LIKE 'tablename' and get the field auto_increment...
treylane
This might be obvious, but it tripped me up - be careful when using last_insert_id() with persistent connections - running last_insert_id() after a failed update/insert/etc will return the last insert id of the last successful update/insert made by that CONNECTION rather than 0 for the number of rows updated by the previous non-working query, and who knows what the last query run on that connection was.
bob m.
There is a problem with the function below submitted by rudolflai In that mysql_autoid function, what happens when between the time you've retrieved the id and the time you do something with it (like INSERT a new record) another new record has been inserted into the database in the interim? Better make sure you LOCK the tables you're working on before you use the function and don't UNLOCK until after you've done something with the id returned. 02-dec-2005 06:48
Take care of setting an empty value for the AUTO_INCREMENT Field else you never get a value except zero returned from mysq_insert_id() .... Ciao Ephraim typer85
Please be warned that this function, like almost every other MySQL function, requires that the same database resource link that was used to insert the data into the database be used to get the last auto increment value. If you close the database connection after inserting data, then open one up again and then attempt to get the last auto increment value, you will get an incorrect value since all resources related to the last insert query were cleaned up after the connection was closed. squezy16
One of the problem of the LAST_INSERT_ID function is that it may return an old Auto_Increment number if the INSERT did not have the time to run properly while the mysql_insert_id always returns the good value. I tried to insert a row imidiatly followed by a select LAST_INSERT_ID and it kept on returning me the LAST_INSERT_ID before my insert statement.
bholbrook
My apologies for the error below (that was modified out of a class) - as you cannot define a constant as an array. replace the line: <? define("ID",...); ?> with <? $mysql_id = mysql_query("..."); ?> $mysql_id is now an array in which the first element $mysql_id[0] holds the last inserted id. Apologies if anyone struggled over that one... esp. the noobs. benfoldsforever
Just wanted to re-iterate previous comment on receiving NULL or 0 return statement from calling mysql_insert_id() after insert statement. If you have multiple mysql connections (i.e. mysql_connect() or mysqli_connect()) on the page you will need to specify the the connection you are using when calling this function! I.e. mysql_insert_id($MY_CONN); jameszhou2001
Just a reminder, mysql_insert_id() should be called after 'mysql_affected_rows()', but BEFORE 'mysql_query("COMMIT")'.
athies
Just a quick note. mysql_insert_id() does work with REPLACE.
brodseba
It's possible to do the same with M$ Server. function odbc_insert_id() { $query = "SELECT @@IDENTITY AS ID;"; $result = odbc_exec($this->m_rConnectionID, $query); $row = odbc_fetch_object($result); return $row->ID; } buana95 att yahoo dott com
It's not true that mysql_insert_id() only returns the ID generated for an AUTO_INCREMENT column by the previous INSERT query. We can use LAST_INSERT_ID() statement that will return value for mysql_insert_id(). Example: $sql = "UPDATE `mytable` SET `mytable_id`= LAST_INSERT_ID(`mytable_id` + 1) WHERE ...; @mysql_query($sql); $last_id = mysql_insert_id(); LAST_INSERT_ID() statement will affect mysql_insert_id(). Regards, Buana bonatoque
It seems that, in case of a very first INSERT, mysql_insert_id() returns 0. My guess is that MySQL does not trigger auto increment if the table is empty. Once an entry is present, it works as expected.
wayne theisinger
In response to treylane at example dot com. It is very very very important that you put in an "or die" or some other form of error handling. Some scripts can fail invisibly and insert invalid data throughout your whole database because of mysql_insert_id inserting the last successful insertid rather than reporting that the last attempt failed. example of an or die statement. $result = mysql_query($sql) or die("Invalid query: " . mysql_error()); $EventID = mysql_insert_id(); sander ad deltaserv d0t nl
In reply to: sly at noiretblanc dot org: Make sure that auto_increment has an capital A as the first letter, otherwise it WON'T work! So you have to spell it as Auto_increment... And then it works fine. frumler
If you want to use the ID that was generated for one table and insert it into a second table, you can use SQL statements like this: INSERT INTO foo (auto,text) VALUES(NULL,'text'); # generate ID by inserting NULL INSERT INTO foo2 (id,text) VALUES(LAST_INSERT_ID(),'text'); # use ID in second table ...found here: http://www.mysql.com/doc/en/Getting_unique_ID.html It works even without inserting the NULL value for some reason ;) The following is great for monitoring: $new_id = mysql_insert_id(); print "New id: $new_id\n"; Hope it helps you all, cheers. steve bond
If you use this function after doing an INSERT ... SELECT to insert multiple rows at once, you get the autonumber ID of the *first* row added by the INSERT. e.g. if there are 4 records in table 'init' that have column 'type' = 2 I want to add these 4 records to table 'game' Table game has an autonumber column 'game_id' that is currently at 32. If I do this query: INSERT INTO game (type, players, rounds) SELECT type, players, rounds FROM init WHERE type = 2 Then mysql_insert_id() will return 33, not 36. heiligkind
If you insert a data row by using the ON DUPLICATE KEY UPDATE clause in an INSERT-statement, the mysql_insert_id() function will return not the same results as if you directly use LAST_INSERT_ID() in MySQL. See the following example: <? // insert a datarow, primary key is auto_increment // value is a unique key $query = "INSERT INTO test (value) VALUES ('test')"; mysql_query( $query ); echo 'LAST_INSERT_ID: ', mysql_query( "SELECT LAST_INSERT_ID()" ), ' mysql_insert_id: ', mysql_insert_id(); ?> This will print: LAST_INSERT_ID: 1 mysql_insert_id: 1 In this case the function returns the same as the MySQL-Statement. But see the insert on an existing key: <? $query = "INSERT INTO test (value) VALUES ('test') ON DUPLICATE KEY UPDATE value = 'test2'"; mysql_query( $query ); echo 'LAST_INSERT_ID: ', mysql_query( "SELECT LAST_INSERT_ID()" ), ' mysql_insert_id: ', mysql_insert_id(); ?> This will print: LAST_INSERT_ID: 2 mysql_insert_id: 1 By using the ON DUPLICATE KEY UPDATE clause, only the old datarow will be modified, if the INSERT statement causes a duplicate entry, but the LAST_INSERT_ID() function returns the next auto_increment value for the primary key, which is by the way not set as the next auto_increment value in the database. The mysql_insert_id() function returns the primary key of the old (and changed) data row. For me this is the right operation method, because the LAST_INSERT_ID() function returns a value which is not referenced to a data row at all. Greets from Munich. heiligkind louis
If mysql_insert_id() returns 0 or null, check your auto increment field is not being set by your sql query, also if you have multiple db connections like I did, the solution is to create a seperate db connection for this query.
arie
I was having problems with this as well. If you need the last inserted id more then one time and mysql_inserted_id() is not working, make a query like this: <?php mysql_query("SELECT LAST_INSERT_ID()"); ?> And then fetch it to save it in php. ben
I realise this isn't the best way of doing it, but if use auto_increment in your tables, which just increases by one every time you add a row, you can get the last used id simply by quering the database, selecting the id column and ordering it descendingly and pulling out the first row returned. The added bonus is you can do it anytime, instead of just after an INSERT query. <?php function previous_id($table, $id_column) { if ($table && $id_column) { $result = mysql_query("SELECT " . $id_column " FROM " . $table . " ORDER BY " . $id_column . " DESC LIMIT 1"); $stuff = mysql_fetch_assoc($result); return $stuff[$id_column]; } else { return false; } } ?> Just change $table to the table name, and $id_column to the column which auto increments. baak
I believe the "resource link" being referred to is not what is returned from mysql_query() but the $link returned from mysql_connect(). mysql_insert_id() will just use the most recent connection if there is no explicit $link being used. So the above example in the manual page itself should behave the same with mysql_insert_id($link) at the end instead of the mysql_insert_id() they used. If you had multiple connections, the $link might come in handy. Also in reading the mysql manual itself, there is some enlightening information on the fact that this does appear to be totally safe to use because it is on a per-connection basis. Here's the relevant quote from the manual on LAST_INSERT_ID() which is located here: http://dev.mysql.com/doc/mysql/en/Information_functions.html "The last ID that was generated is maintained in the server on a per-connection basis. This means the value the function returns to a given client is the most recent AUTO_INCREMENT value generated by that client. The value cannot be affected by other clients, even if they generate AUTO_INCREMENT values of their own. This behavior ensures that you can retrieve your own ID without concern for the activity of other clients, and without the need for locks or transactions." Sounds safe to me. I couldn't imagine this would be done any other way *but* on a per-connection basis, otherwise chaos would ensue. The only way to test it would be to perform a multi-thread type test. Perhaps someone is up for it and wants to post their results somewhere? :) rudolflai
Hi, Below is a snippet for retriving the next insert id from a mysql table. It functions like the auto_increment option in phpMyAdmin. Hope you find it helpful. =] <?php function mysql_autoid($id,$table){ $query = 'SELECT MAX('.$id.') AS last_id FROM '.$table; $result = mysql_query($query); $result = mysql_fetch_array($result); return $result[last_id]+1; } /// usage mysql_autoid('nID','news'); ?> Cheers, Rudolf james dot baxter
Have had many people coming to me with issues regarding last_insert_id and mysql_insert_id() etc This is a very simple solution that caters for most. As you can see it gets the last auto inc from the field, in this case, ID. mysql_query("LOCK TABLES art WRITE"); mysql_query("INSERT INTO table (....) VALUES (....)"); $result = mysql_query("SELECT MAX(ID) AS LAST_ID FROM table"); $result = mysql_fetch_array($result); mysql_query("UNLOCK TABLES"); echo "Last ID#" . $result[LAST_ID]; foros _at_ anthalia.com
Forget about using MAX to get the last inserted id. Race conditions like other users inserting between your SELECT MAX(.. and your INSERT may render your id unusable. The WAY to get the id is by using mysql_insert_id() or the mysql SQL function LAST_INSERT_ID(). Take care, if using mysql_insert_id() you should provide the resource returned by the mysql_connect, not the resultset returned by mysql_query. ed
Beware, mysql_insert_id() only returns the value of the last syntaxically correct insert statement. If your code has a problem and the insert is not understood by the server then the value of the last working insert command is returned. Put something else in place such as "select count( id ) from table" before and after the mysql_insert_id() call to ensure that a row was inserted. john k.
Be careful when using "insert ignore". If the unique index already exists, the record will not be added, but it WILL give you the id of the next auto_increment value even though it didn't create it. <?php $sql = "insert ignore into sometable set num=10"; mysql_query($sql) or die(); echo mysql_affected_rows()." "; echo mysql_insert_id()." "; // same record, database is unique on 'num' $sql = "insert ignore into sometable set num=10"; mysql_query($sql) or die(); echo mysql_affected_rows()." "; echo mysql_insert_id()." "; ?> would give: 1 116372 0 116373 soroushl
As mentioned by frumler at the-beach dot no_spam dot net the LAST_INSERT_ID works like a charm when inserting values into tables. I'm not sure why anyone would need mysql_insert_id() when LAST_INSERT_ID is readily available. example: Say you have a table called "transaction" and a table called "accounts". Obviously each account must be created using a transaction, so every time a record is created in the accounts table, a record must be created in the transaction table containing the same account_id(auto_increment) that was just created by mysql. Here's a simple way to do this: <?php $account_query="INSERT INTO accounts (account_id,type) VALUES (NULL,'saving')"; $transaction_query="INSERT INTO transactions(transaction_id,account_id) VALUES (NULL,LAST_INSERT_ID)"; $a_query=mysql_query($account_query); $t_query=mysql_query($transaction_query); ?> dtez
any zerofills on your id get chopped off on this function because it returns an int.
guelphdad
and the primary reason to use neither of those last two solutions is both could result in race conditions when there is more than a single user with access to the database. when you use MAX or ORDER BY DESC LIMIT 1 you will retrieve the maximum value from the table, at that moment. That doesn't mean another user doesn't do an insertion in the primary and secondary table BEFORE you do your insertion in the secondary table. You have thus inserted a row with a correct id into the second table. Always use last_insert_id()
bholbrook
An effective way to retrieve the last insert id without fail or having two queries inserted at the same time causing an unexpected number being returned. <? mysql_query("LOCK TABLES apc_forms WRITE"); mysql_query("SET AUTOCOMMIT = 0"); mysql_query("INSERT INTO apc_forms (form_title, form_event_id, form_expirey) VALUES ('title',1,'2005-10-10')"); define('ID',mysql_query("SELECT LAST_INSERT_ID()")); mysql_query("COMMIT"); mysql_query("UNLOCK TABLES"); ?> relic
A bit more on return values: mysql_insert_id() returns 0 if you haven't actually manipulated anything yet. Also, it returns 0 even if the DB connection is lost[0] between inserting and calling mysql_insert_id() - so you can always count on getting an integer. [0] By 'lost' I mean e.g. a DB crash. Actually closing the open link and then trying to communicate with the DB will of course result in an error. |
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