PHP skip duplicates - php

Question

I have serious question about importing data from CSV to Database.
Import script:
if (file_exists('temp.csv')) {
$i=0;
require "connection.php";
$handle = fopen("temp.csv", "r");
try {
$import= $db->prepare("INSERT INTO adherence(
dateandtime,
lastname,
firstname,
paidtime,
approvedtime,
notadhering) VALUES(
?,?,?,?,?,?)");
$i = 0;
while (($data = fgetcsv($handle, 1000, ",", "'")) !== FALSE) {
if($i > 0) {
$data = str_replace('"', '', $data);
$myDate = date("Y/m/d",strtotime(str_replace('/','-',$data[0])));
$import->bindParam(1, $myDate, PDO::PARAM_STR);
$import->bindParam(2, $data[1], PDO::PARAM_STR);
$import->bindParam(3, $data[2], PDO::PARAM_STR);
$import->bindParam(4, $data[3], PDO::PARAM_STR);
$import->bindParam(5, $data[4], PDO::PARAM_STR);
$import->bindParam(6, $data[5], PDO::PARAM_STR);
$import->execute();
}
$i++;
}
fclose($handle);
Problem is, I need some sort of conditional logic to check, if row allready exist in database before importing, and skip it - if it exist. How to handle this kind of thing?

Answer 1

Basically you have two different ways to approach it.
1. via the rdbms:
Use an unique index in your table. Once you insert a duplicate,
you'll encounter an error, which can be properly displayed/logged/whatever.
2. via application logic:
Search for your item before inserting with a proper SELECT statement.. If
you find a match, don't insert it.
Example:
$sth = $db->prepare("SELECT yourfields FROM yourtable WHERE yourcondition = :cond");
$sth->bindParam(':cond',$yourvariable, PDO::PARAM_STR);
$sth->execute();
if ($sth->rowCount() > 0) {
// results - don't insert
} else {
// place your insert terms here
}
In most conditions, coders will implement the first way, since it reduces traffic between application and RDBMS and makes your data model more robust. If this is any issue, try the second way.