Updating a row with query language, mysql, php

Question

I have a basic question for you experts,

I want to update a row in mysql database by using the User_Id of an entry. I created User_Id as auto increment, primary key. Now for the last user I calculated its necessary variables, now I want to add that variable to the last user's necessary column through its User_id.

The name of the variable I want to add is $improvement. I wrote the code below, however I dont now how to do that depending on its User_Id.

$sql = "
UPDATE users 
SET Improvement='$improvement'
WHERE ... )
";  

mysql_query($sql, $accounts);

I dont know what to write to the "..." part in the code. Please give me feedback if you see a problem in my question. I can give my table if you need.

Answer 1

mysql updating last inserted id

I guess I found the answer in that link:

$sql = "
UPDATE users 
SET Improvement='$improvement'
WHERE User_id = LAST_INSERT_ID() )
";  

However I am not sure if "SET Improvement='$improvement'" part is the correct syntax

Answer 2

If your user_id is primary index then you can use

$sql = " UPDATE users SET Improvement='$improvement' order by user_id DESC limit 1 ) ";

mysql_query($sql, $accounts);