add basic event objects

console/migrations/m181205_050104_create_trigger_event_registration.php

@@ -0,0 +1,41 @@
+<?php
+
+use yii\db\Schema;
+use yii\db\Migration;
+
+class m181205_050104_create_trigger_event_registration extends Migration
+{
+    public function up()
+    {
+        $this->addColumn('{{%event}}',"seat_count",$this->integer());
+        $this->execute("CREATE TRIGGER event_seat_count_check
+                 AFTER INSERT ON event_registration FOR EACH ROW
+                 BEGIN
+                      IF (SELECT coalesce(COUNT(id),0) FROM event_registration
+                           WHERE canceled_at is null AND id_event = NEW.id_event) 
+                           >
+                           (SELECT coalesce(seat_count,0) from event where id_event = NEW.id_event)
+                      THEN
+                           SIGNAL SQLSTATE '45000'
+                                SET MESSAGE_TEXT = 'MAX_SEAT_COUNT_EXCEEDED';
+                      END IF;
+                 END;
+        ");
+    }
+
+    public function down()
+    {
+        $this->execute("DROP TRIGGER IF EXISTS event_seat_count_check;");
+    }
+
+    /*
+    // Use safeUp/safeDown to run migration code within a transaction
+    public function safeUp()
+    {
+    }
+
+    public function safeDown()
+    {
+    }
+    */
+}