How do I find out a specific row ID from a table? - php

Question

Hello I’m working on a project (I’m a total newbie), here ‘s how the project goes…
I’ve created a Create User page, the user puts in the credentials and click on Create Account.
This redirects to another page (process.php) where all MySQL queries are executed-
Note: ID is set to Auto Increment, Not Null, Primary Key. All the data is inserted dynamically, so I don’t know which Username belongs to which ID and so on.
$query = “INSERT INTO users (Username, Something, Something Else) VALUES (‘John’, ‘Smith’, ‘Whatever’ )”
Everything gets stored into the “users” table.
Then it gets redirected to another page (content.php) where the User can review or see his/her credentials.
The problem is, I use SELECT * FROM users and mysql_fetch_array() but it always gives me the User with ID = 1 and not the current User (suppose user with ID = 11). I have no idea how to code this.
There are suppose 50 or more rows,
how can I retrieve a particular row if I don’t know its ID or any of its other field’s value?

Answer 1

You may use:
mysql_insert_id();
Get the ID generated in the last query. Reference: http://us1.php.net/mysql_insert_id
This function return the ID generated for an AUTO_INCREMENT column by the previous query on success, 0 if the previous query does not generate an AUTO_INCREMENT value, or FALSE if no MySQL connection was established.
Now you have the id, add that to your WHERE clause.
Note: It would be better if you use mysqli.

Answer 2

You are using mysql_fetch_array() just once, so it is getting you just one row.
what you are writing:
<?php
include('connection.php'); //establish connection in this file.
$sql = "select * from users";
$result = mysql_query($sql);
$row = mysql_fetch_array($result);
echo(row['id']);
?>
What should be there to fetch all the rows:
<?php
include('connection.php'); //establish connection in this file.
$sql = "select * from users";
$result = mysql_query($sql);
while($row = mysql_fetch_array($result))
{
echo(row['id']);
}
?>
Now, what you need, is to get the user id of the registered user at that time.
For that, you need to create a session. Add session_start(); in your process.php and create a session there. Now to get the last id you have to make a query:
select *
from users
where id = (select max(id) from users);
Now this will give you the last id created. Store that in a session variable.
$_SESSION['id']=$id;
Now, on content.php add this:
session_start();
echo($_SESSION['id']);

Answer 3

You have to use WHERE:
SELECT * FROM users WHERE ID = 11
If you dont use WHERE, it will select all users, and your mysql_fetch_assoc will get you one row of all (ie. where ID = 1).
PS: mysql_* is deprecated, rather use mysqli_*.

Answer 4

Using mysql_ commands:
$query = "INSERT INTO users (`Username`, `Something`, `Something Else`) VALUES ('John', 'Smith', 'Whatever' )";
$result = mysql_query($query) or die( mysql_error() );
$user_id = mysql_insert_id();
header("Location: content.php?id=".$user_id);
Or another way to pass $user_id to your next page
$_SESSION['user_id'] = $user_id;
header("Location: content.php");
Using mysqli_ commands:
$query = "INSERT INTO users (`Username`, `Something`, `Something Else`) VALUES ('John', 'Smith', 'Whatever' )";
$result = mysqli_query($dbConn, $query) or die( printf("Error message: %s\n", mysqli_error($dbConn)) );
$user_id = mysqli_insert_id($dbConn);