在 Yii 2.0 中创建了一个新的数据库迁移对象：添加 4 个字段的最佳实践

1、表名：cpa_channel_app_source 设计，表前缀：cpa_，如图1

2、查看命令：yii migrate/create 的帮助文档

PS E:\wwwroot\channel-pub-api> ./yii help migrate/create

DESCRIPTION
                    "
Creates a new migration.

This command creates a new migration using the available migration template.
After using this command, developers should modify the created migration
skeleton by filling up the actual migration logic.

yii migrate/create create_user_table

In order to generate a namespaced migration, you should specify a namespace before the migration's name.
Note that backslash (\) is usually considered a special character in the shell, so you need to escape it
properly to avoid shell errors or incorrect behavior.
For example:

yii migrate/create 'app\\migrations\\createUserTable'

In case [[migrationPath]] is not set and no namespace is provided, the first entry of [[migrationNamespaces]] will be used.


USAGE

yii migrate/create <name> [...options...]

- name (required): string
  the name of the new migration. This should only contain
  letters, digits, underscores and/or backslashes.

  Note: If the migration name is of a special form, for example create_xxx or
  drop_xxx, then the generated migration file will contain extra code,
  in this case for creating/dropping tables.


OPTIONS

--appconfig: string
  custom application configuration file path.
  If not set, default application configuration is used.

--color: boolean, 0 or 1
  whether to enable ANSI color in the output.
  If not set, ANSI color will only be enabled for terminals that support it.

--comment, -C: string (defaults to '')
  the comment for the table being created.

--compact, -c: boolean, 0 or 1 (defaults to 0)
  indicates whether the console output should be compacted.
  If this is set to true, the individual commands ran within the migration will not be output to the console.
  Default is false, in other words the output is fully verbose by default.

--db: Connection|array|string (defaults to 'db')
  the DB connection object or the application component ID of the DB connection to use
  when applying migrations. Starting from version 2.0.3, this can also be a configuration array
  for creating the object.

--fields, -f: array
  column definition strings used for creating migration code.

  The format of each definition is `COLUMN_NAME:COLUMN_TYPE:COLUMN_DECORATOR`. Delimiter is `,`.
  For example, `--fields="name:string(12):notNull:unique"`
  produces a string column of size 12 which is not null and unique values.

  Note: primary key is added automatically and is named id by default.
  If you want to use another name you may specify it explicitly like
  `--fields="id_key:primaryKey,name:string(12):notNull:unique"`

--help, -h: boolean, 0 or 1
  whether to display help information about current command.

--interactive: boolean, 0 or 1 (defaults to 1)
  whether to run the command interactively.

--migration-namespaces: array
  list of namespaces containing the migration classes.

  Migration namespaces should be resolvable as a [path alias](guide:concept-aliases) if prefixed with `@`, e.g. if you specify
  the namespace `app\migrations`, the code `Yii::getAlias('@app/migrations')` should be able to return
  the file path to the directory this namespace refers to.
  This corresponds with the [autoloading conventions](guide:concept-autoloading) of Yii.

  For example:

  ```php
  [
      'app\migrations',
      'some\extension\migrations',
  ]
  ```

--migration-path, -p: string|array
  the directory containing the migration classes. This can be either
  a [path alias](guide:concept-aliases) or a directory path.

  Migration classes located at this path should be declared without a namespace.
  Use [[migrationNamespaces]] property in case you are using namespaced migrations.

  If you have set up [[migrationNamespaces]], you may set this field to `null` in order
  to disable usage of migrations that are not namespaced.

  Since version 2.0.12 you may also specify an array of migration paths that should be searched for
  migrations to load. This is mainly useful to support old extensions that provide migrations
  without namespace and to adopt the new feature of namespaced migrations while keeping existing migrations.

  In general, to load migrations from different locations, [[migrationNamespaces]] is the preferable solution
  as the migration name contains the origin of the migration in the history, which is not the case when
  using multiple migration paths.

--migration-table, -t: string (defaults to '{{%migration}}')
  the name of the table for keeping applied migration information.

--template-file, -F:  (defaults to '@yii/views/migration.php')

--use-table-prefix, -P: boolean, 0 or 1 (defaults to 1)
  indicates whether the table names generated should consider
  the `tablePrefix` setting of the DB connection. For example, if the table
  name is `post` the generator wil return `{{%post}}`.

3、添加字段，如果迁移的名称遵循 add_xxx_to_yyy 这样的格式，生成的类文件将会包含必要的 addColumn 和 dropColumn。你可以像如下这样指定多个字段：yii migrate/create add_xxx_column_yyy_column_to_zzz_table –fields=”xxx:integer,yyy:text”。如图2

PS E:\wwwroot\channel-pub-api> ./yii migrate/create add_group_name_column_name_column_avatar_column_fans_count_column_to_channel_app_source_table --fields="group_name:string(64):notNull:defaultValue(''),name:string(32):notNull:defaultValue(''),avatar:string:notNull:defaultValue(''),fans_count:integer:notNull:defaultValue(0)"
Yii Migration Tool (based on Yii v2.0.35)

Create new migration 'E:\wwwroot\channel-pub-api\console/migrations\m201014_055436_add_group_name_column_name_column_avatar_column_fans_count_column_to_channel_app_source_table.php'? (yes|no) [no]:yes
New migration created successfully.

4、生成 PHP 类文件：m201014_055436_add_group_name_column_name_column_avatar_column_fans_count_column_to_channel_app_source_table.php。

<?php

use yii\db\Migration;

/**
 * Handles adding columns to table `{{%channel_app_source}}`.
 */class m201014_055436_add_group_name_column_name_column_avatar_column_fans_count_column_to_channel_app_source_table extends Migration
{
    /**
     * {@inheritdoc}
     */    public function safeUp()
    {
        $this->addColumn('{{%channel_app_source}}', 'group_name', $this->string(64)->notNull()->defaultValue(''));
        $this->addColumn('{{%channel_app_source}}', 'name', $this->string(32)->notNull()->defaultValue(''));
        $this->addColumn('{{%channel_app_source}}', 'avatar', $this->string()->notNull()->defaultValue(''));
        $this->addColumn('{{%channel_app_source}}', 'fans_count', $this->integer()->notNull()->defaultValue(0));
    }

    /**
     * {@inheritdoc}
     */    public function safeDown()
    {
        $this->dropColumn('{{%channel_app_source}}', 'group_name');
        $this->dropColumn('{{%channel_app_source}}', 'name');
        $this->dropColumn('{{%channel_app_source}}', 'avatar');
        $this->dropColumn('{{%channel_app_source}}', 'fans_count');
    }
}

5、编辑 PHP 类文件：m201014_055436_add_group_name_column_name_column_avatar_column_fans_count_column_to_channel_app_source_table.php。以添加其他的字段选项：字段注释、字段顺序。

<?php

use yii\db\Migration;

/**
 * Handles adding columns to table `{{%channel_app_source}}`.
 */class m201014_055436_add_group_name_column_name_column_avatar_column_fans_count_column_to_channel_app_source_table extends Migration
{
    /**
     * {@inheritdoc}
     */    public function safeUp()
    {
        $this->addColumn('{{%channel_app_source}}', 'group_name', $this->string(64)->notNull()->defaultValue('')->comment('租户名称')->after('group_id'));
        $this->addColumn('{{%channel_app_source}}', 'name', $this->string(32)->notNull()->defaultValue('')->comment('名称')->after('channel_type_code'));
        $this->addColumn('{{%channel_app_source}}', 'avatar', $this->string()->notNull()->defaultValue('')->comment('头像')->after('name'));
        $this->addColumn('{{%channel_app_source}}', 'fans_count', $this->integer()->notNull()->defaultValue(0)->comment('粉丝数')->after('avatar'));
    }

    /**
     * {@inheritdoc}
     */    public function safeDown()
    {
        $this->dropColumn('{{%channel_app_source}}', 'group_name');
        $this->dropColumn('{{%channel_app_source}}', 'name');
        $this->dropColumn('{{%channel_app_source}}', 'avatar');
        $this->dropColumn('{{%channel_app_source}}', 'fans_count');
    }
}

6、提交迁移，为了将数据库升级到最新的结构，你应该使用如下命令来提交所有新的迁移。如图3

PS E:\wwwroot\channel-pub-api> ./yii migrate
Yii Migration Tool (based on Yii v2.0.35)

Total 1 new migration to be applied:
        m201014_055436_add_group_name_column_name_column_avatar_column_fans_count_column_to_channel_app_source_table

Apply the above migration? (yes|no) [no]:yes
*** applying m201014_055436_add_group_name_column_name_column_avatar_column_fans_count_column_to_channel_app_source_table
    > add column group_name string(64) NOT NULL DEFAULT '' COMMENT '租户名称' AFTER `group_id` to table {{%channel_app_source}} ... done (time: 0.108s)
    > add column name string(32) NOT NULL DEFAULT '' COMMENT '名称' AFTER `channel_type_code` to table {{%channel_app_source}} ... done (time: 0.097s)
    > add column avatar string NOT NULL DEFAULT '' COMMENT '头像' AFTER `name` to table {{%channel_app_source}} ... done (time: 0.170s)
    > add column fans_count integer NOT NULL DEFAULT 0 COMMENT '粉丝数' AFTER `avatar` to table {{%channel_app_source}} ... done (time: 0.158s)
*** applied m201014_055436_add_group_name_column_name_column_avatar_column_fans_count_column_to_channel_app_source_table (time: 0.551s)


1 migration was applied.

Migrated up successfully.

7、查看最新的表设计，符合预期，如图4