MySQL operates the database to encapsulate the function of adding, deleting, modifying and checking

SqlTool.class.php

<?php 

    class SqlTool{
        private $conn;
        private $host = "localhost";
        private $user = "root";
        private $password = "root";
        private $db = "test1";

        /*
            连接数据库的构造方法
        */
        function SqlTool(){
            $this->conn = mysql_connect($this->host , $this->user , $this->password);
            if(!$this->conn){
                die('连接失败'.mysql_error());
            }

            mysql_select_db($this->db,$this->conn);
            mysql_query('set names gbk');
        }

        //select
        function execute_dql($sql){
            $res = mysql_query($sql,$this->conn);
            return $res;
        }

        //insert、update、delete
        function execute_dml($sql){
            $obj = mysql_query($sql,$this->conn);
            if(!$obj){
                //return 0;//操作失败
                die('操作失败'.mysql_error());
            }else{
                if(mysql_affected_rows($this->conn)>0){
                    //return 1;//操作成功
                    echo "操作成功";
                }else{
                    //return 2;//行数没有收到影响
                    die('行数没有受影响');
                }
            }
        }   
    }   

?>

SqlToolTest.php

<?php 
    //引入数据库类文件
    require_once "SqlTool.class.php";

    //----------------dml操作------------------
    //插入
    //$sql = "insert into user1(name , password , email , age) values('李四',md5('123'),'[email protected]',18)";

    //删除
    //$sql = "delete from user1 where id = 9";

    //更新
    //$sql = "update user1 set id=4 where name='李四'";

    //创建一个SqlTool对象
    //$SqlTool = new SqlTool();

    //$res = $SqlTool->execute_dml($sql);

    //--------------------dql操作--------------------
    $sql = "select * from user1";

    //创建一个SqlTool对象
    $SqlTool = new SqlTool();

    $res = $SqlTool->execute_dql($sql);

    while($row=mysql_fetch_row($res)){
        foreach($row as $key=>$val){
            echo "--$val";
        }
        echo "<br>";
    }

    mysql_free_result($res);

    /*if($res==0){
        die('操作失败'.mysql_error());
    }else if($res==1){
        echo "操作成功";
    }else if($res==2){
        echo "行数没有受影响";
    }*/
?>

Create database
create database test1;

Create data table

create table user1(
id int auto_increment primary key,
name varchar(32) not null,
password varchar(64) not null,
email varchar(128) not null,
age tinyint unsigned not null
);

Table Structure

The picture result of the follow-up operation: