Yii迁移不起作用

我的Yii迁移有问题。问题是，我迁移了一个成功迁移后成功完成的代码。我尝试了另一个迁移代码，但这向我展示了迁移代码，第一个我已经迁移，第二个我需要迁移。我只是继续告诉yii继续迁移，这之后给我发了一个错误，迁移已经完成，现在是我已经完成的迁移，所以第二次迁移无法完成。然后我删除了我的第一个迁移代码，然后继续迁移我的第二个代码。代码已成功执行，但没有创建表。有人能解决这个问题吗，为什么我的迁移没有完成，是的，我执行的第二个代码，最后一个表在迁移文件夹的safeup（）和safedown（）上。

这是我的代码，但它再次向我发送错误。事实上，我正在从trackstar项目中学习yii。所以，这是我的代码，我把它放在up函数中再次出错。你能看看吗

    public function up()
    {
        //create the issue table
        $this->createTable('tbl_issue', array(
                'id' => 'pk',
                'name' => 'string NOT NULL',
                'description' => 'text',
                'project_id' => 'int(11) DEFAULT NULL',
                'type_id' => 'int(11) DEFAULT NULL',
                'status_id' => 'int(11) DEFAULT NULL',
                'owner_id' => 'int(11) DEFAULT NULL',
                'requester_id' => 'int(11) DEFAULT NULL',
                'create_time' => 'datetime DEFAULT NULL',
                'create_user_id' => 'int(11) DEFAULT NULL',
                'update_time' => 'datetime DEFAULT NULL',
                'update_user_id' => 'int(11) DEFAULT NULL',
        ), 'ENGINE=InnoDB');
        //create the user table
        $this->createTable('tbl_user', array(
                'id' => 'pk',
                'username' => 'string NOT NULL',
                'email' => 'string NOT NULL',
                'password' => 'string NOT NULL',
                'last_login_time' => 'datetime DEFAULT NULL',
                'create_time' => 'datetime DEFAULT NULL',
                'create_user_id' => 'int(11) DEFAULT NULL',
                'update_time' => 'datetime DEFAULT NULL',
                'update_user_id' => 'int(11) DEFAULT NULL',
        ), 'ENGINE=InnoDB');
        //create the assignment table that allows for many-to-many
        //relationship between projects and users
        $this->createTable('tbl_project_user_assignment', array(
                'project_id' => 'int(11) NOT NULL',
                'user_id' => 'int(11) NOT NULL',
                'PRIMARY KEY (`project_id`,`user_id`)',
        ), 'ENGINE=InnoDB');
        //foreign key relationships
        //the tbl_issue.project_id is a reference to tbl_project.id
        $this->addForeignKey("fk_issue_project", "tbl_issue", "project_
            id", "tbl_project", "id", "CASCADE", "RESTRICT");
        //the tbl_issue.owner_id is a reference to tbl_user.id
        $this->addForeignKey("fk_issue_owner", "tbl_issue", "owner_id",
                "tbl_user", "id", "CASCADE", "RESTRICT");
        //the tbl_issue.requester_id is a reference to tbl_user.id
        $this->addForeignKey("fk_issue_requester", "tbl_issue",
                "requester_id", "tbl_user", "id", "CASCADE", "RESTRICT");
        //the tbl_project_user_assignment.project_id is a reference totbl_project.id
        $this->addForeignKey("fk_project_user", "tbl_project_user_
assignment", "project_id", "tbl_project", "id", "CASCADE",
                "RESTRICT");
        //the tbl_project_user_assignment.user_id is a reference to tbl_user.id
        $this->addForeignKey("fk_user_project", "tbl_project_user_
        assignment", "user_id", "tbl_user", "id", "CASCADE", "RESTRICT");
    }
    public function down()
    {
    $this->truncateTable('tbl_project_user_assignment');
        $this->truncateTable('tbl_issue');
        $this->truncateTable('tbl_user');
        $this->dropTable('tbl_project_user_assignment');
        $this->dropTable('tbl_issue');
        $this->dropTable('tbl_user');
    }
`

迁移代码已经粘贴好了，这就是它现在开始向我显示的错误。这里是到dropbox的链接，这是它在这里的链接描述中显示的错误