Fix migration issue with fields that might already exist in the database - refs CT#7892

app/Migrations/Schema/V110/Version20150522222222.php

@@ -17,9 +17,41 @@ class Version20150522222222 extends AbstractMigrationChamilo
      */
     public function up(Schema $schema)
     {
-        $this->addSql('ALTER TABLE user ADD COLUMN last_login datetime DEFAULT NULL');
+        // The first ALTER queries here requires a check because the field might already exist
+        $connection = $this->connection;
+        $fieldExists = false;
+        $sql = "SELECT *
+                FROM user
+                LIMIT 1";
+        $result = $connection->executeQuery($sql);
+        $dataList = $result->fetchAll();
+        if (!empty($dataList)) {
+            foreach ($dataList as $data) {
+                if (isset($data['last_login'])) {
+                    $fieldExists = true;
+                }
+            }
+        }
+        if (!$fieldExists) {
+            $this->addSql('ALTER TABLE user ADD COLUMN last_login datetime DEFAULT NULL');
+        }
         // calendar events comments
-        $this->addSql("ALTER TABLE c_calendar_event ADD COLUMN comment TEXT");
+        $fieldExists = false;
+        $sql = "SELECT *
+                FROM c_calendar_event
+                LIMIT 1";
+        $result = $connection->executeQuery($sql);
+        $dataList = $result->fetchAll();
+        if (!empty($dataList)) {
+            foreach ($dataList as $data) {
+                if (isset($data['comment'])) {
+                    $fieldExists = true;
+                }
+            }
+        }
+        if (!$fieldExists) {
+            $this->addSql("ALTER TABLE c_calendar_event ADD COLUMN comment TEXT");
+        }
 
         // Move some settings from configuration.php to the database
         // Current settings categories are: