What are the potential challenges when trying to combine tables from multiple MDB files in a single SQL query using PHP?

When trying to combine tables from multiple MDB files in a single SQL query using PHP, one potential challenge is that you need to establish separate database connections for each MDB file and then perform a JOIN operation on the tables from these connections. This can be cumbersome and may require additional error handling to ensure the connections are established successfully. 

<?php

// Establish connection to the first MDB file
$conn1 = new PDO("odbc:Driver={Microsoft Access Driver (*.mdb)};Dbq=path/to/first.mdb");
$conn1->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

// Establish connection to the second MDB file
$conn2 = new PDO("odbc:Driver={Microsoft Access Driver (*.mdb)};Dbq=path/to/second.mdb");
$conn2->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

// Perform a JOIN operation on tables from both connections
$query = "SELECT * FROM table1 INNER JOIN table2 ON table1.id = table2.id";
$stmt = $conn1->query($query);

// Fetch and display results
while ($row = $stmt->fetch()) {
    print_r($row);
}

// Close connections
$conn1 = null;
$conn2 = null;

?>

Keywords

PHP SQL query MDB files combine tables challenges

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