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can i update table and set JSON string with PDO? Because PDO is removing "\" character and diacritics is not working please help.
->query("UPDATE products SET name = '".$new_name."' WHERE shop = '1' AND id = 'a9t8'");
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You are using PDO yet still open to SQL injection.
You should prepare your query, that's the whole point of PDO
$sql = "UPDATE products SET name = :new_name WHERE shop = :shop AND id = :id";
$statement = $conn->prepare($sql);
$statement->bindValue(":new_name", $new_name);
$statement->bindValue(":shop", '1');
$statement->bindValue(":id", 'a9t8');
$statement->execute();