According to the PHP documentation, mysql_insert_id takes the last inserted id from the mysql table.
My question is, if I have a website that inserts more than 2 rows per second to the DB, can I use the mysql_insert_id and get the correct ID I am referring to in the INSERT query a line before?
From the MySQL manual:
The ID that was generated is maintained in the server on a per-connection basis. This means that the value returned by the function to a given client is the first AUTO_INCREMENT value generated for most recent statement affecting an AUTO_INCREMENT column by that client. This value cannot be affected by other clients, even if they generate AUTO_INCREMENT values of their own. This behavior ensures that each client can retrieve its own ID without concern for the activity of other clients, and without the need for locks or transactions.
Short version: it is safe to use.
mysql_insert_id gives you the insert id of the most recent INSERT statement on the connection you give it.
If you call this immediatly after your insert, on the same mysql connection, you get the inserted id matching that insert statement, independantly of any other inserts going on in the mean time.
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According to the PHP documentation, mysql_insert_id takes the last inserted id from the mysql table.
My question is, if I have a website that inserts more than 2 rows per second to the DB, can I use the mysql_insert_id and get the correct ID I am referring to in the INSERT query a line before?
From the MySQL manual:
The ID that was generated is maintained in the server on a per-connection basis. This means that the value returned by the function to a given client is the first AUTO_INCREMENT value generated for most recent statement affecting an AUTO_INCREMENT column by that client. This value cannot be affected by other clients, even if they generate AUTO_INCREMENT values of their own. This behavior ensures that each client can retrieve its own ID without concern for the activity of other clients, and without the need for locks or transactions.
Short version: it is safe to use.
mysql_insert_id gives you the insert id of the most recent INSERT statement on the connection you give it.
If you call this immediatly after your insert, on the same mysql connection, you get the inserted id matching that insert statement, independantly of any other inserts going on in the mean time.
According to the PHP documentation, mysql_insert_id takes the last inserted id from the mysql table.
My question is, if I have a website that inserts more than 2 rows per second to the DB, can I use the mysql_insert_id and get the correct ID I am referring to in the INSERT query a line before?
From the MySQL manual:
The ID that was generated is maintained in the server on a per-connection basis. This means that the value returned by the function to a given client is the first AUTO_INCREMENT value generated for most recent statement affecting an AUTO_INCREMENT column by that client. This value cannot be affected by other clients, even if they generate AUTO_INCREMENT values of their own. This behavior ensures that each client can retrieve its own ID without concern for the activity of other clients, and without the need for locks or transactions.
Short version: it is safe to use.
mysql_insert_id gives you the insert id of the most recent INSERT statement on the connection you give it.
If you call this immediatly after your insert, on the same mysql connection, you get the inserted id matching that insert statement, independantly of any other inserts going on in the mean time.
I'm using mysql_insert_id() to fetch the last inserted id. I have a confusion about which id it gives when inserting values concurrently by multiple users at the same instance. Does it gives the one that I have inserted or does it compare the last query within same instance?
The short answer to your question is: the last one you inserted.
Here's why.
The php functions that retrieve the last inserted ids are wrappers around the mysql library function mysql_insert_id(). The server tracks the most recently generated AUTO_INCREMENT value on a per connection basis, and is not affected by another connection generating an AUTO_INCREMENT value.
20.6.14.3 How to Get the Unique ID for the Last Inserted Row
For LAST_INSERT_ID(), the most recently generated ID is maintained in
the server on a per-connection basis. It is not changed by another
client. It is not even changed if you update another AUTO_INCREMENT
column with a nonmagic value (that is, a value that is not NULL and
not 0). Using LAST_INSERT_ID() and AUTO_INCREMENT columns
simultaneously from multiple clients is perfectly valid. Each client
will receive the last inserted ID for the last statement that client
executed.
I need to return the value from my auto incremented column of the update that's just happened.
Basically I am updating a user with XYZ values:
$stmt->execute();
I need to get the new records value from ID column in the database which is auto incremented.
PDO lastInsertId(); just returns the latest record and could be potentially dangerous on a high traffic site?
I hope you are using MySql??
From mysql site:
The ID that was generated is maintained in the server on a per-connection basis. This means that the value returned by the function to a given client is the first AUTO_INCREMENT value generated for most recent statement affecting an AUTO_INCREMENT column by that client. This value cannot be affected by other clients, even if they generate AUTO_INCREMENT values of their own. This behavior ensures that each client can retrieve its own ID without concern for the activity of other clients, and without the need for locks or transactions.
Further:
If you insert multiple rows using a single INSERT statement, LAST_INSERT_ID() returns the value generated for the first inserted row only.
So it's save to use because it works on connection basis. And if you insert multiple rows you can combine it with PDO's rowCount method to get all inserted id's.
According to the PHP documentation, mysql_insert_id takes the last inserted id from the mysql table.
My question is, if I have a website that inserts more than 2 rows per second to the DB, can I use the mysql_insert_id and get the correct ID I am referring to in the INSERT query a line before?
From the MySQL manual:
The ID that was generated is maintained in the server on a per-connection basis. This means that the value returned by the function to a given client is the first AUTO_INCREMENT value generated for most recent statement affecting an AUTO_INCREMENT column by that client. This value cannot be affected by other clients, even if they generate AUTO_INCREMENT values of their own. This behavior ensures that each client can retrieve its own ID without concern for the activity of other clients, and without the need for locks or transactions.
Short version: it is safe to use.
mysql_insert_id gives you the insert id of the most recent INSERT statement on the connection you give it.
If you call this immediatly after your insert, on the same mysql connection, you get the inserted id matching that insert statement, independantly of any other inserts going on in the mean time.