Add upgrade note for 2.0.50 (#20200)

framework/UPGRADE.md

@@ -51,6 +51,114 @@ if you want to upgrade from version A to version C and there is
 version B between A and C, you need to follow the instructions
 for both A and B.
 
+Upgrade from Yii 2.0.50
+-----------------------
+
+* Correcting the behavior for `JSON` column type in `MariaDb`.
+
+Example usage of `JSON` column type in `db`:
+
+```php
+<?php
+
+use yii\db\Schema;
+
+$db = Yii::$app->db;
+$command = $db->createCommand();
+
+// Create a table with a JSON column
+$command->createTable(
+    'products',
+    [
+        'id' => Schema::TYPE_PK,
+        'details' => Schema::TYPE_JSON,
+    ],
+)->execute();
+
+// Insert a new product
+$command->insert(
+    'products',
+    [
+        'details' => [
+            'name' => 'apple',
+            'price' => 100,
+            'color' => 'blue',
+            'size' => 'small',
+        ],
+    ],
+)->execute();
+
+// Read all products
+$records = $db->createCommand('SELECT * FROM products')->queryAll();
+```
+
+Example usage of `JSON` column type in `ActiveRecord`:
+
+```php
+<?php
+
+namespace app\model;
+
+use yii\db\ActiveRecord;
+
+class ProductModel extends ActiveRecord
+{
+    public static function tableName()
+    {
+        return 'products';
+    }
+
+    public function rules()
+    {
+        return [
+            [['details'], 'safe'],
+        ];
+    }
+}
+```
+
+```php
+<?php
+
+use app\model\ProductModel;
+
+// Create a new product
+$product = new ProductModel();
+
+// Set the product details
+$product->details = [
+    'name' => 'windows',
+    'color' => 'red',
+    'price' => 200,
+    'size' => 'large',
+];
+
+// Save the product
+$product->save();
+
+// Read the first product
+$product = ProductModel::findOne(1);
+
+// Get the product details
+$details = $product->details;
+
+echo 'Name: ' . $details['name'];
+echo 'Color: ' . $details['color'];
+echo 'Size: ' . $details['size'];
+
+// Read all products with color red
+$products = ProductModel::find()
+    ->where(new \yii\db\Expression('JSON_EXTRACT(details, "$.color") = :color', [':color' => 'red']))
+    ->all();
+
+// Loop through all products
+foreach ($products as $product) {
+    $details = $product->details;
+    echo 'Name: ' . $details['name'];
+    echo 'Color: ' . $details['color'];
+    echo 'Size: ' . $details['size'];
+}
+```
 
 Upgrade from Yii 2.0.48
 -----------------------