Merge branch 'yiisoft:allow-columninterface-as-type' into allow-colum…

…ninterface-as-type

UPGRADE.md

@@ -1,14 +1,18 @@
 # Upgrading Instructions for Yii Database
 
-This file contains the upgrade notes for the Yii Database.
-These notes highlight changes that could break your application when you upgrade it from one version to another.
-Even though we try to ensure backwards compatibility (BC) as much as possible, sometimes
-it isn't possible or very complicated to avoid it and still create a good solution to
-a problem. While upgrade to Yii 3.0 might require substantial changes to both your application and extensions,
-the changes are bearable and require "refactoring", not "rewrite".
-All the "Yes, it is" cool stuff, and Yii soul is still in place.
-
-Changes summary:
-
-* `Yiisoft\Db\Connection::$charset` has been removed. All supported PDO classes allow you to specify the connection
-  charset in the DSN.
+The following upgrading instructions are cumulative. That is, if you want to upgrade from version A to version C and 
+there is version B between A and C, you need to following the instructions for both A and B.
+
+## Upgrade from 1.x to 2.x
+
+Add `ColumnInterface` support and change type of parameter `$type` from `string` to `ColumnInterface|string` 
+in `addColumn()` method of your classes that implement the following interfaces:
+
+- `Yiisoft\Db\Command\CommandInterface`;
+- `Yiisoft\Db\QueryBuilder\DDLQueryBuilderInterface`;
+
+… or inherit from the following classes:
+
+- `Yiisoft\Db\Command\AbstractCommand`;
+- `Yiisoft\Db\QueryBuilder\AbstractDDLQueryBuilder`;
+- `Yiisoft\Db\QueryBuilder\AbstractQueryBuilder`.