About database and model usage of ThinkPHP5

1, TP5 database architecture

Db:  是TP5操作数据库的入口类。它的作用是为连接数据库做准备，我们只需要在database.php里填写相应的配置即可。

Connection: 是TP5的连接器类，因为TP5支持四种数据库（Mysql，Pgsql，Sqlite，Sqlsrv），所以TP5封装了一个类来提供统一的调用接口来支持我们连接数据库（这里的连接是惰性连接，只有在执行SQL的时候才会真正连接）。

Query: 查询器，因为不同数据库的SQL语句不同，所以封装了一个Query类来提供统一的接口，以实现不同数据库的CURD操作。查询器是TP5数据访问层的核心，它连接了Connection和Builder。

Builder: 生成器。这个类主要是把Query的查询参数生成相应的sql语句，然后把其返回给Connection供其使用。

2, Database access

In TP5, there are three methods for database access:

1. Native sql statement.

Db::query('select * from think_user where id=?',[8]);
Db::execute('insert into think_user (id, name) values (?, ?)',[8,'thinkphp']);

1. Query constructor

It should be noted that the above In the query method, find, select, insert, update, and delete are all query operations, and the others are auxiliary operations. The auxiliary operations return an object and support chain calls. But once the query operation is executed, it cannot be called further.

The order of different auxiliary operations has no effect, but the order of the same auxiliary operations will.

不同的辅助操作，先后顺序没影响。Db::table('banner')->where('id', '>', '2')->order('update_time asc')->select();Db::table('banner')->order('update_time asc')->where('id', '>', '2')->select();

相同的查询操作，先后顺序有影响。
$list = Db::table('data')
    ->where('id', '>', 1)
    ->where('name', 'like', '%think%')
    ->order('id', 'desc')
    ->order('create_time', 'desc')
    ->limit(8)
    ->select();
$list = Db::table('data')
    ->where('name', 'like', '%think%')
    ->where('id', '>', 1)
    ->order('create_time', 'desc')
    ->order('id', 'desc')
    ->limit(8)
    ->select();

1. Model

ORM Object Relation Mapping Object relational mapping

is mapped to our database through the model table, and then operate the database by operating the model.

We compare it with the query constructor

// 查询操作$user = Db::table('user')->find(1);// 取值操作echo $user['name'];echo $user['email'];// 设置操作$user['name']  = 'topthink';$user['email'] = 'thinkphp@qq.com';// 更新操作Db::table('user')->update($user);

If it is a model operation, it can be implemented corresponding to the following code

// 查询操作$user = User::get(1);// 取值操作echo $user->name;
echo $user->email;// 设置操作$user->name  = 'topthink';$user->email = 'thinkphp@qq.com';// 更新操作$user->save();

This is outside the model, and also It is the value acquisition and setting operations in the controller, but inside the model, the following method is used:

// 取值操作echo $user->getData('name');
echo $user->getData('email');// 设置操作echo $user->data('name', 'SpawN');
echo $user->data('email', '123@qq.com');

CURD operation of the model

Creation

Db usage:

Db::table('user')->insert([    'name' => 'spawn',    'email' => '123@qq.com'])

Model usage:

$user = new User;$user->save([    'name' => 'spawn',    'email' => '123@qq.com'])$user = User::create([    'name' => 'sapwn',    'email' => '123@qq.com'])

Summary:

• save (dynamic) Returns: Number of affected records

• create(static) Returns: model object instance (method can be called directly)

Read

Db:

$user = Db::table('user')->where('id', 1)->find();

Model:

$user = User::get(1);

It should be noted that find and select are methods of the query constructor, and get and all are methods of the model. But the model is based on the query constructor, so the model can call the find and select methods, but the query constructor cannot call the get and all methods

Summary:

Method Function Return value
get Query a single record Model object instance
find Query a single record Model object instance
all Query multiple records based on the primary key Array or data set containing model object instances
select Query multiple records based on conditions Containing model object instances Array or data set

Update

Db:

Db::table('user')->where('id', 1)->update([    'name' => 'haha',    'email' => 'heihei@qq.com'])

Model:

$user = User::get(1);$user->save([    'name' => 'haha',    'email' => 'heihei@qq.com'])

或者 

User::update([    'name'  => 'topthink',    'email' => 'topthink@qq.com',
], ['id' => 1]);

Summary:

Method Function Return value
save Update data Number of records affected
update Update data (static) Return model object instance

需要注意的是，模型的更新操作是只更新有变化的数据。性能比较好。

Delete

Db:

Db::table('user')->delete(1);

Model:

$user = User::get(1);$user->delete();
或者
User::destory(1);

Summary:

Method Function Return value
delete Delete current data Number of records affected
destroy Delete specified data (static) Affected Number of records

Now that we have mastered the basic CURD operations of the model, let’s summarize the method differences:

Usage Db class model (dynamic) Model (static)
Create insert save create
Update update save update
Read a single find find get
Read multiple select select all
Delete delete delete destroy destroy

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