How to use PHP for database operations?

The previous article introduced you to "PHP Advanced Practice-What are the member attributes of the file upload class?" 》, this article continues to introduce to you how to use PHP to perform database operations, which has certain reference value. Friends in need can refer to it. I hope it will be helpful to everyone.

PHP Advanced Practice-Database Operation Class

Mainstream PHP Development Framework

Parent Class (Mode1 Class)

1. Review of sql statements

insert into user (name, age, money) values (' abc', 18， 1000) ;
update user set age=20， money=1500 where id=1;
delete from user where id=2;
select * from user where id=3 group by . . . having . . . order by ..limit

We still take the code as an example, create a new file and define a class class. When we encapsulate the model class, we need Add member variables, such as host name, user name, password, database name, character set and data table prefix. Then after we successfully connect to the database, a resource will be returned, and we need to save the resource as a member variable so that we can use it elsewhere It is very convenient to use, so we add database connection resources and data table names (you can specify the table name yourself). We often have some errors when debugging the database, so we need SQL statements and operation arrays to debug errors. All query conditions are stored;

The specific code is as follows:

<?php
class Model
{
  //主机名.
  protected $host;
  //用户名.
  protected $user;
  //密码
  protected $pwd;
  //数据库名
  protected $dbname;
 //字符集
 protected $charset;
 //数据表前缀
 protected $prefix;
 //数据库连接资源
 protected $link;
 //数据表名     这里可以自己指定表名
 protected $tableName ;
 //sql语句
 protected $sql;
 //操作数组存放的就是所有的查询条件
 protected $options；
}

Because there are many member variables, we need to initialize her,

//filed method

//table method

/ /where method

//group method

/ /having method

//order method

//limit method

, we can splice the SQL statements based on these methods, and only in this way can we implement the query. We need two methods when querying, one is query and the other is exec method; the code is as follows:

 //构造方法，对成员变量进行初始化
 function_construct()
 {
 }
我们构造完之后，上面刚刚写的代码都需要初始化，太多，我们可以传递一个数组进来，
  function_construct( $config)
  {
  //对成员变量一一进行初始化
  $this->host = $config['DB_HOST'];
  $this->user = $config['DB_USER'];
  $this->pwd = $config['DB_PWD'] ;
  $this ->dbname = $config['DB_NAME ' j;
  $this->charset = $config['DB_CHARSET'] ;
  $this->prefix = $config['DB_PREFIX'] ;
  }
  紧接着我们需要连接数据库：
  //连接数据库
  $this->link = $this ->connect();
}
protected function connect( )
{
  $link = mysqli_connect($this->host, $this->user,$this->pwd) ; .
if (!$link) {
die('数据库连接失败');
  }

//Select database

mysqli_select_db($link, $this->dbname);

//Settings Character set

mysqli_set_charset($link, $this->charset);

//Return the resource with successful connection

return $link;
 }

Recommended tutorial: "MySQL Tutorial"

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