How can one efficiently select data from two tables on two servers in PHP while excluding already displayed entries in the second selection?

When selecting data from two tables on two servers in PHP while excluding already displayed entries in the second selection, you can achieve this by using a combination of SQL queries and PHP code. One way to do this is to first retrieve the data from the first table on the first server, store the already displayed entries in an array, and then use a WHERE NOT IN clause in the second SQL query to exclude these entries from the second selection. 

// Connect to the first server
$server1_connection = mysqli_connect('server1', 'username', 'password', 'database1');

// Retrieve data from the first table on the first server
$query1 = "SELECT * FROM table1";
$result1 = mysqli_query($server1_connection, $query1);

// Store already displayed entries in an array
$excluded_entries = array();
while ($row = mysqli_fetch_assoc($result1)) {
    $excluded_entries[] = $row['id'];
}

// Connect to the second server
$server2_connection = mysqli_connect('server2', 'username', 'password', 'database2');

// Select data from the second table on the second server excluding already displayed entries
$query2 = "SELECT * FROM table2 WHERE id NOT IN (" . implode(',', $excluded_entries) . ")";
$result2 = mysqli_query($server2_connection, $query2);

// Display the results from the second selection
while ($row = mysqli_fetch_assoc($result2)) {
    // Display data from table2
}

Keywords

PHP MySQL JOIN UNION EXCEPT

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