Select from database only values not seen before [closed] - php

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Let's say that I have a database with this data stored:
Email-Link-Link2
1E#231-Example1-Example2
1E#231-Example3-Example4
How can I select all of this value with a PDO query excluding those seen before, so in this case 1E#231,will select only one time.

Answer 1

If understand what you said, this is your answer:
Connexion to data base with PDO
<?php
//CONNEXION TO DATA BASE WITH PDO...
$pdo_options[PDO::ATTR_ERRMODE] = PDO::ERRMODE_EXCEPTION;
$base = new PDO('mysql:host=localhost;dbname=your_data_base', 'the_user', 'Your_password', $pdo_options);
//end of connexion to data_base
;?>
NOW getting data from data base with not duplication(you can use sql function DISTINCT
<?php
$sc=$base->query("SELECT DISTINCT Email FROM table_where_data_stored");
while($data_distinct =$sc->fetch()){
//your data will be displayed here
;}
;?>
May this help you!!

Answer 2

To evade double selection commonly one use the DISTINCT statement, like this:
SELECT DISTINCT *
FROM myTable
But the best way to evade double-selection is to evade redundant entries to the database. As far as I understand the two entries in your database the second one is an update, and you don't want to overwrite the previous entry. This is a well known problem, and commonly solved like this:
There is a certain date from when on the new eMail should be used, so add a field "valid_from" and add this WHERE statement to your query:
WHERE valid_from > GETDATE()
GETDATE() returns a datetime, therefore it's enough to select "greater than".