Can't select from sys.extended_properties using PHP PDO - php

Question

When querying a SQL Server database from PHP with this statement:
SELECT [Value] FROM sys.extended_properties WHERE name='MS_Description'
I get this error message:
"Fatal error: Uncaught exception 'PDOException' with message 'SQLSTATE[IMSSP]: Invalid type.' in C:\inetpub\wwwroot\index.php:104 Stack trace: #0 C:\inetpub\wwwroot\index.php(104): PDOStatement->fetch(2) #1 {main} thrown in C:\inetpub\wwwroot\index.php on line 104"
The php that I'm using is below, line 104 is the start of the While loop:
$sql = "SELECT [Value] FROM sys.extended_properties WHERE name='MS_Description'";
global $pdo;
$qry = $pdo->query($sql);
if (!$qry) {
exit('<pre>' . print_r($qry->errorInfo()));
}
while($row = $qry->fetch(PDO::FETCH_ASSOC)) {
foreach ($row as $key => $value) {
echo '<p>Key: ' .$key. ', Value: ' .$value. '</p>';
}
}
The code above works fine when selecting from any other table or view e.g:
SELECT * FROM sys.events
If I execute the statement via SSMS it works fine, any ideas why it doesn't work via PHP?

Answer 1

Casting the columns being selected as varchar(255) solved the problem i.e.
$sql = "SELECT CAST([Value] AS VARCHAR(255)) FROM sys.extended_properties WHERE name='MS_Description'";
Got to the solution based on the answers to this question and this question.