PHP/MySQL insert row then get 'id'

$link = mysqli_connect('127.0.0.1', 'my_user', 'my_pass', 'my_db');
mysqli_query($link, "INSERT INTO mytable (1, 2, 3, 'blah')");
$id = mysqli_insert_id($link);

See mysqli_insert_id().

Whatever you do, don't insert and then do a "SELECT MAX(id) FROM mytable". Like you say, it's a race condition and there's no need. mysqli_insert_id() already has this functionality.

Another way would be to run both queries in one go, and using MySQL's LAST_INSERT_ID() method, where both tables get modified at once (and PHP does not need any ID), like:

mysqli_query($link, "INSERT INTO my_user_table ...;
  INSERT INTO my_other_table (`user_id`) VALUES (LAST_INSERT_ID())");

Note that Each connection keeps track of ID separately (so, conflicts are prevented already).

The MySQL function LAST_INSERT_ID() does just what you need: it retrieves the id that was inserted during this session. So it is safe to use, even if there are other processes (other people calling the exact same script, for example) inserting values into the same table.

The PHP function mysql_insert_id() does the same as calling SELECT LAST_INSERT_ID() with mysql_query().

As to PHP's website, mysql_insert_id is now deprecated and we must use either PDO or MySQLi (See @Luke's answer for MySQLi). To do this with PDO, proceed as following:

$db = new PDO('mysql:dbname=database;host=localhost', 'user', 'pass');
$statement = $db->prepare('INSERT INTO people(name, city) VALUES(:name, :city)');
$statement->execute([':name' => 'Bob', ':city' => 'Montreal']);

echo $db->lastInsertId();

As @NaturalBornCamper said, mysql_insert_id is now deprecated and should not be used. The options are now to use either PDO or mysqli. NaturalBornCamper explained PDO in his answer, so I'll show how to do it with MySQLi (MySQL Improved) using mysqli_insert_id.

// First, connect to your database with the usual info...
$db = new mysqli($hostname, $username, $password, $databaseName);
// Let's assume we have a table called 'people' which has a column
// called 'people_id' which is the PK and is auto-incremented...
$db->query("INSERT INTO people (people_name) VALUES ('Mr. X')");
// We've now entered in a new row, which has automatically been 
// given a new people_id. We can get it simply with:
$lastInsertedPeopleId = $db->insert_id;
// OR
$lastInsertedPeopleId = mysqli_insert_id($db);

Check out the PHP documentation for more examples: http://php.net/manual/en/mysqli.insert-id.php

I just want to add a small detail concerning lastInsertId();

When entering more than one row at the time, it does not return the last Id, but the first Id of the collection of last inserts.

Consider the following example

$sql = 'INSERT INTO my_table (varNumb,userid) VALUES
     (1, :userid),
     (2, :userid)';
$sql->addNewNames = $db->prepare($sql);
addNewNames->execute(array(':userid' => $userid));

echo $db->lastInsertId();

What happens here is that I push in my_table two new rows. The id of the table is auto-increment. Here, for the same user, I add two rows with a different varNumb.

The echoed value at the end will be equal to the id of the row where varNumb=1, which means not the id of the last row, but the id of the first row that was added in the last request.

An example.

    $query_new = "INSERT INTO students(courseid, coursename) VALUES ('', ?)";
    $query_new = $databaseConnection->prepare($query_new);
    $query_new->bind_param('s', $_POST['coursename']);
    $query_new->execute();
    $course_id = $query_new->insert_id;
    $query_new->close();

The code line $course_id = $query_new->insert_id; will display the ID of the last inserted row. Hope this helps.

Try like this you can get the answer:

<?php
$con=mysqli_connect("localhost","root","","new");
// Check connection
if (mysqli_connect_errno())
  {
  echo "Failed to connect to MySQL: " . mysqli_connect_error();
  }

mysqli_query($con,"INSERT INTO new values('nameuser','2015-09-12')");

// Print auto-generated id
echo "New record has id: " . mysqli_insert_id($con);

mysqli_close($con);
?>

Have a look at following links:

http://www.w3schools.com/php/func_mysqli_insert_id.asp

http://php.net/manual/en/function.mysql-insert-id.php

Also please have a note that this extension was deprecated in PHP 5.5 and removed in PHP 7.0

I found an answer in the above link http://php.net/manual/en/function.mysql-insert-id.php

The answer is:

mysql_query("INSERT INTO tablename (columnname) values ('$value')");        
echo $Id=mysql_insert_id();

Try this... it worked for me!

$sql = "INSERT INTO tablename (row_name) VALUES('$row_value')";
    if (mysqli_query($conn, $sql)) {
    $last_id = mysqli_insert_id($conn);
    $msg1 = "New record created successfully. Last inserted ID is: " . $last_id;
} else {
    $msg_error = "Error: " . $sql . "<br>" . mysqli_error($conn);
    }

Another possible answer will be:

When you define the table, with the columns and data it'll have. The column id can have the property AUTO_INCREMENT.

By this method, you don't have to worry about the id, it'll be made automatically.

For example (taken from w3schools )

CREATE TABLE Persons
(
ID int NOT NULL AUTO_INCREMENT,
LastName varchar(255) NOT NULL,
FirstName varchar(255),
Address varchar(255),
City varchar(255),
PRIMARY KEY (ID)
)

Hope this will be helpful for someone.

Edit: This is only the part where you define how to generate an automatic ID, to obtain it after created, the previous answers before are right.