doc updated for using with raw php

Author: sujancse

README.md

@@ -16,14 +16,14 @@ $columns = [
     'email'
 ];
 
-$exporter = new Export(
-    User::query(),
-    $columns
-);
+$users = User::query(); // Query builder
 
-$exporter->export();
+Exporter::init($users, $columns, 'users.csv');
+Exporter::export();
 ```
 
+Or you can pass `Collection` or `Array`. But it is **highly recommended** to pass the **`Query Builder`** as it will use generator to save memory usage.
+
 **For eloquent relation**
 ```$xslt
 $columns = [
@@ -43,3 +43,43 @@ $exporter->export();
 ```
 
 Where `user` is the relation name, which is same as is in the `$columns` variable.
+
+## Usage with raw PHP (PDOStatement)
+
+Usage with PDO is straight forward. You **MUST** have to add the following code
+```$xslt
+$stmt->setFetchMode(PDO::FETCH_ASSOC); // N.B. must be included
+```
+
+And then pass the `$stmt` to `Exporter`
+```$xslt
+    $servername = "localhost";
+    $username = "root";
+    $password = "password";
+    $dbname = "laravel";
+
+    $columns = [
+        'id',
+        'name',
+        'email'
+    ];
+
+    try {
+        $conn = new PDO("mysql:host=$servername;dbname=$dbname", $username, $password);
+        $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
+        $stmt = $conn->prepare("SELECT id, name, email FROM users");
+        $stmt->execute();
+
+        // set the resulting array to associative
+        $stmt->setFetchMode(PDO::FETCH_ASSOC);
+
+        Exporter::init($stmt, $userData, 'users.csv');
+        Exporter::export();
+    }
+    catch(PDOException $e) {
+        echo "Error: " . $e->getMessage();
+    }
+    $conn = null;
+```
+
+## You are always welcome to contribute