The implementation result of mysql_query () is always false.

The execution result of mysql_query () has always been false1. Currently, one database named test has only one table, student. Attribute Name: ID, Name, Email.2) tries to encapsulate database connections and operations into a DatabaseManager class, and extends the execution result of a class StudentDetail mysql_query () to false.
1) a database named test has only one student.
Attribute Name: ID, Name, Email.
2) try to encapsulate database connections and operations into a class DatabaseManager, and extend the class StudentDetailsDataManager to obtain student information.
3) problem: you can connect to the test Database. the SQL statement has been tested in the database, but the result of executing the SQL statement mysql_query () is always false. What's the problem?

The code is as follows:
Database operation base class: DatabaseManager

PHP code

  //DatabaseManager.php
  connection = $connection;            $this->connection = $close_flag;        }                protected function db_open(){            if(empty($this->connection)){                $this->connection = mysql_connect($this->host,$this->user,$this->psw);                if (!$this->connection) {                    $this->db_handle_error_connetion();                    return false;                }                if (!mysql_select_db($this->name,$this->connection)) {                    $this->da_handle_select();                    return false;                }            }        }                        public function db_close(){            if($this->connection)                mysql_close($this->connection);        }                protected function db_handle_error_connetion(){            echo 'Failed connetion';        }        protected function db_handle_select(){            echo 'Failed access database!';        }    }?>

------
Derived class: StudentDetailsDataManager

PHP code

  //StudentDetailsDataManager.php
  host = "localhost";            $this->user = "root";            $this->psw = "root";            $this->name = "test";            $this->db_open();            }                public function getStudentInfo($ID,&$data){            //$query = "SELECT * FROM student WHERE ID ='$ID'";            $query = "select * from student where ID = '$ID'";            $result = mysql_query($query);            //print_r($result);            if (!$result) {                echo "result is empty!!";                return false;            }                        $data = mysql_fetch_array($result,MYSQL_ASSOC);            mysql_free_result($result);        }    }?>

----
Use the StudentDetailsDataManager instance to obtain student information

PHP code

  
  getStudentInfo($ID, $data);    $stuDataManager->db_close();    echo $data["ID"];?>

------ Solution --------------------
Mysql_error: Check it out.
------ Solution --------------------
Public function _ construct ($ connection, $ close_flag ){
$ This-> connection = $ connection;
$ This-> connection = $ close_flag;
}
Can't you see such a serious error?

In addition
If (! Mysql_select_db ($ this-> name, $ this-> connection )){