Error: Duplicate entry '1' for key 'r_id' - php

Question

Here's the table structure
CREATE TABLE IF NOT EXISTS `result` (
`res_id` int(11) NOT NULL AUTO_INCREMENT,
`s_id` int(10) NOT NULL,
`i_id` int(6) NOT NULL,
`r_status` text NOT NULL,
`r_score` decimal(6,0) NOT NULL,
PRIMARY KEY (`res_id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=2 ;
I've searched for a solution and have tried on different occasions, building the table from scratch, drop and import it back, checked the index. As you can see, I've renamed the id to res_id but when I run it on the browser the error still shows r_id.
If it makes a difference, when the id is not set to auto increment, the same error pops up.
Here's the code snippet for the page where I want to insert into the database.
//retrieve existing r_id
$sql_res = "SELECT res_id FROM result ORDER BY res_id DESC LIMIT 1";
$query_res = mysql_query($sql_res) or die("MySQL Error: " . mysql_error());
$data_res = mysql_fetch_assoc($query_res);
$resid_count = $data_res['res_id']+1;
//echo "<br>Result: " . $resid_count;
// insert result to table
$sql_result = "INSERT INTO result (res_id, r_score, s_id, i_id) VALUES ('" . $resid_count . "', '" . $correct . "', '" . $id . "', '" . $ins_id . "')";
mysql_query($sql_result) or die ("Error: " . mysql_error());
EDIT: I changed the code like you guys suggested. Took the res_id out from the INSERT. It still says duplicate entry for r_id. I went ahead for trial and error and created another table 'score' with the same structure to replace 'result'. Was wondering if the same table name was giving it problem (could running the page many times cause this?). Same outcome with the score table.
Any help would be greatly appreciated. I'm stuck here and cannot proceed with my project. Thanks.
Atikah

Answer 1

Since res_idis AUTO_INCREMENTI suggest that you replace your insert query by this:
$sql_result = "INSERT INTO result (r_score, s_id, i_id) VALUES ('". $correct . "', '" . $id . "', '" . $ins_id . "')";

Answer 2

try this
$sql_result = "INSERT INTO result ( r_score, s_id, i_id) VALUES ( '" . $correct . "', '" . $id . "', '" . $ins_id . "')";
res_id will be automatically inserted without your inserting
EDIT.
If you want just insert then you dont need those lines , just remove them, because you are using them for knowing the last res_id . since res_id as i said before its auto_increment. it will increment automatically
$sql_res = "SELECT res_id FROM result ORDER BY res_id DESC LIMIT 1";
$query_res = mysql_query($sql_res) or die("MySQL Error: " . mysql_error());
$data_res = mysql_fetch_assoc($query_res);
$resid_count = $data_res['res_id']+1;

Answer 3

Make sure you don't use apostrophes in your SQL where you use numerics (int). This could cause trouble. And res_id should not be involved at all, because that's the point with having autoincremental columns (You don't have search for the next id in the database with PHP-code, DB takes care of that)
Your code could be translated into two lines:
$sql_result = "INSERT INTO result (r_score, s_id, i_id) VALUES (" . $correct . ", " . $id . ", " . $ins_id . ")";
mysql_query($sql_result) or die ("Error: " . mysql_error());
OR (variables inside quotes gives the actual values)
$sql_result = "INSERT INTO result (r_score, s_id, i_id) VALUES ($correct, $id, $ins_id)";
mysql_query($sql_result) or die ("Error: " . mysql_error());
and of course - don't use mysql_* - functions, cause they're deprecated. Use PDO or Mysqli instead with parameters so you could avoid SQL injection in a safe way. The code you've got is vulnerable to SQL injections.