DBAL-126 - Special case for dropping MySQL Primary keys

lib/Doctrine/DBAL/Platforms/MySqlPlatform.php

@@ -20,7 +20,9 @@
 namespace Doctrine\DBAL\Platforms;
 
 use Doctrine\DBAL\DBALException,
-    Doctrine\DBAL\Schema\TableDiff;
+    Doctrine\DBAL\Schema\TableDiff,
+    Doctrine\DBAL\Schema\Index,
+    Doctrine\DBAL\Schema\Table;
 
 /**
  * The MySqlPlatform provides the behavior, features and SQL dialect of the
@@ -577,19 +579,36 @@ class MySqlPlatform extends AbstractPlatform
      */
     public function getDropIndexSQL($index, $table=null)
     {        
-        if($index instanceof \Doctrine\DBAL\Schema\Index) {
-            $index = $index->getQuotedName($this);
-        } else if(!is_string($index)) {
+        if($index instanceof Index) {
+            $indexName = $index->getQuotedName($this);
+        } else if(is_string($index)) {
+            $indexName = $index;
+        } else {
             throw new \InvalidArgumentException('MysqlPlatform::getDropIndexSQL() expects $index parameter to be string or \Doctrine\DBAL\Schema\Index.');
         }
         
-        if($table instanceof \Doctrine\DBAL\Schema\Table) {
+        if($table instanceof Table) {
             $table = $table->getQuotedName($this);
         } else if(!is_string($table)) {
             throw new \InvalidArgumentException('MysqlPlatform::getDropIndexSQL() expects $table parameter to be string or \Doctrine\DBAL\Schema\Table.');
         }
         
-        return 'DROP INDEX ' . $index . ' ON ' . $table;
+        if ($index instanceof Index && $index->isPrimary()) {
+            // mysql primary keys are always named "PRIMARY", 
+            // so we cannot use them in statements because of them being keyword.
+            return $this->getDropPrimaryKeySQL($table);
+        }
+
+        return 'DROP INDEX ' . $indexName . ' ON ' . $table;
+    }
+    
+    /**
+     * @param Index $index
+     * @param Table $table 
+     */
+    protected function getDropPrimaryKeySQL($table)
+    {
+        return 'ALTER TABLE ' . $table . ' DROP PRIMARY KEY';
     }
     
     /**