The Laravel Schema class provides a database agnostic way of manipulating tables. It works well with all of the databases supported by Laravel, and has a unified API across all of these systems.
laravel 的 Schema 类提供一套操作 laravel 所支持的所有数据库的封装.
To create a new database table, the Schema::create method is used:
Schema::create 用来创建一个数据库表:
Schema::create('users', function($table)
{
$table->increments('id');
});
The first argument passed to the create method is the name of the table, and the second is a Closure which will receive a Blueprint object which may be used to define the new table.
create 方法的第一个参数是表明，第二个参数是一个闭包 Closure 函数，返回定义表结构的 Blueprint 对象。
To rename an existing database table, the rename method may be used:
rename 方法重命名已经存在的表:
Schema::rename($from, $to);
To specify which connection the schema operation should take place on, use the Schema::connection method:
Schema::connection 方法可以指定操作的数据库连接:
Schema::connection('foo')->create('users', function($table)
{
$table->increments('id'):
});
To drop a table, you may use the Schema::drop method:
Schema::drop 和 Schema::dropIfExists 用来删除表:
Schema::drop('users');
Schema::dropIfExists('users');
To update an existing table, we will use the Schema::table method:
如果要更新一个表的结构，可以使用 Schema::table 方法:
Schema::table('users', function($table)
{
$table->string('email');
});
The table builder contains a variety of column types that you may use when building your tables:
表构建器支持以下列类型：
| 命令 | 描述 |
|---|---|
$table->increments('id'); |
Incrementing ID to the table (primary key). |
$table->string('email'); |
VARCHAR equivalent column |
$table->string('name', 100); |
VARCHAR equivalent with a length |
$table->integer('votes'); |
INTEGER equivalent to the table |
$table->bigInteger('votes'); |
BIGINT equivalent to the table |
$table->smallInteger('votes'); |
SMALLINT equivalent to the table |
$table->float('amount'); |
FLOAT equivalent to the table |
$table->decimal('amount', 5, 2); |
DECIMAL equivalent with a precision and scale |
$table->boolean('confirmed'); |
BOOLEAN equivalent to the table |
$table->date('created_at'); |
DATE equivalent to the table |
$table->dateTime('created_at'); |
DATETIME equivalent to the table |
$table->time('sunrise'); |
TIME equivalent to the table |
$table->timestamp('added_on'); |
TIMESTAMP equivalent to the table |
$table->timestamps(); |
Adds created_at and updated_at columns |
$table->softDeletes(); |
Adds deleted_at column for soft deletes |
$table->text('description'); |
TEXT equivalent to the table |
$table->binary('data'); |
BLOB equivalent to the table |
$table->enum('choices', array('foo', 'bar')); |
ENUM equivalent to the table |
->nullable() |
Designate that the column allows NULL values |
->default($value) |
Declare a default value for a column |
->unsigned() |
Set INTEGER to UNSIGNED |
If you are using the MySQL database, you may use the after method to specify the order of columns:
使用的是 MySQL 的话，还可以通过 after 方法指定列的顺序:
** after 方法指定列顺序**
$table->string('name')->after('email');
To rename a column, you may use the renameColumn method on the Schema builder:
用 renameColumn 方法重命名列：
重命名列
Schema::table('users', function($table)
{
$table->renameColumn('from', 'to');
});
注意: 不支持重命名
enum类型的列
删除 users 表的列 votes
Schema::table('users', function($table)
{
$table->dropColumn('votes');
});
删除多列
Schema::table('users', function($table)
{
$table->dropColumn('votes', 'avatar', 'location');
});
You may easily check for the existence of a table or column using the hasTable and hasColumn methods:
可以使用 hasTable 检查表、hasColumn 检查列是否存在：
检查表
if (Schema::hasTable('users'))
{
//
}
检查列
if (Schema::hasColumn('users', 'email'))
{
//
}
The schema builder supports several types of indexes. There are two ways to add them. First, you may fluently define them on a column definition, or you may add them separately:
schema 构建器支持多种类型的索引，可以通过在创建表的列定义时指定索引或者另外单独添加索引。
定义列时指定索引
$table->string('email')->unique();
可单独添加的索引如下:
| 命令 | 描述 |
|---|---|
$table->primary('id'); |
添加主键 |
$table->primary(array('first', 'last')); |
添加复合键 |
$table->unique('email'); |
添加唯一索引 |
$table->index('state'); |
添加一般索引 |
Laravel also provides support for adding foreign key constraints to your tables:
laravel 也支持外键:
添加外键
$table->foreign('user_id')->references('id')->on('users');
In this example, we are stating that the user_id column references the id column on the users table.
上面我们把 users 表的 id 关联为当前表 user_id 列的外键(?译者注：不知道咋描述，真累)。
You may also specify options for the "on delete" and "on update" actions of the constraint:
还可以指定 on delete 和 on update 的选项:
$table->foreign('user_id')
->references('id')->on('users')
->onDelete('cascade');
To drop a foreign key, you may use the dropForeign method. A similar naming convention is used for foreign keys as is used for other indexes:
dropForeign 方法可以删除外键，[?译者注: 这句没明白] A similar naming convention is used for foreign keys as is used for other indexes:
$table->dropForeign('posts_user_id_foreign');
To drop an index you must specify the index's name. Laravel assigns a reasonable name to the indexes by default. Simply concatenate the table name, the names of the column in the index, and the index type. Here are some examples:
删除索引需要指定索引名，索引名遵循规范： 表名_列名_索引类型:
| 命令 | 描述 |
|---|---|
$table->dropPrimary('users_id_primary'); |
删除 users 表的 id 主键 |
$table->dropUnique('users_email_unique'); |
删除 users 表的 email 列的唯一索引 |
$table->dropIndex('geo_state_index'); |
删除 geo 表的 state 列的索引 |
To set the storage engine for a table, set the engine property on the schema builder:
创建表的时候设置 engine 属性来指定存储引擎:
Schema::create('users', function($table)
{
$table->engine = 'InnoDB';
$table->string('email');
});