PHP PDO-使用bindParam插入INTO不起作用

Question

I stucked at this little piece of code:

$fruit_object = new fruit(1234, 'apple', 'red apple');    

try {
    $dbh = new PDO('mysql:host=localhost;charset=utf8;dbname=database', 'user', 'password');
    $exc = $dbh->prepare("INSERT INTO fruit( type, name) VALUES (:type, :name);");                               
    //$exc->bindParam(':id',   $fruit_object->id,   PDO::PARAM_INT);
    $exc->bindParam(':type', $fruit_object->type, PDO::PARAM_STR);
    $exc->bindParam(':name', $fruit_object->name, PDO::PARAM_STR);
    $exc->execute();
    $dbh = null;
    $exc = null;
} catch (PDOException $e) {
    //this function just do an echo with static content
    $this->error_database($e);
    $dbh = null;
    $exc = null;
    die();
}

I already used PDO for SELECTING things from my database, but with INSERTING something, it does not work. The user has the access to only INSERT stuff - i already tried that on my backend successfully.

So here is the error:

Fatal error: Uncaught Error: Cannot access private property fruit_object::$type

This is my fruit_object class:

<?php


class fruit
{
private $id;
private $type;
private $name;

function __construct($id, $type, $name)
{
    $this->id = $id;
    $this->type = $type;
    $this->name = $name;

}

function __toString()
{
    return $this->name;
}
}

For martin:

INSERT INTO fruit (id, type, name) VALUES (DEFAULT, 'apple', 'red apple');

My database is running on a MySQL server - is this the cause ? Do i have to work with questionmarks (?)?

Thank you, Louis

Answer 1

You are missing closing brace for prepare and semi colon

$exc = $dbh->prepare("INSERT INTO fruit(id, type, name) VALUES (:id, :type, :name)");

if not working then add this line to check error

print_r($exc->errorInfo());

Answer 2

Answering Question 1:

PHP PDO - INSERT INTO with bindParam does not work

If you're inserting an ID into an auto increment field and you've already inserted then it will cause a MySQL error (dupliate A_I field value) – Martin

---

Yeah i know that, I am using the DEFAULT keyword in my real statement. – louis12356

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explain; default keyword for what? – Martin

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There is a SQL keyword 'DEFAULT' which automaticly counts the ID up. – louis12356

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You should not be supplying a value for your Auto Increment ( id ) column. What it looks like is that you're giving a MySQL Instruction via PDO variable which will Never Work . This is because PDO uses Prepared Statements and so variables are only ever going to be variables and can never be instructions .

The Default keyword in MySQL is an instruction to the MySQL program. This instruction will be ignored, not only because it is disallowed but also because you're passing a STRING value to PDO INSERT which claims it should be an INT :

 $exc->bindParam(':id',   $fruit_object->id,   PDO::PARAM_INT);

If $fruit_object->id == "DEFAULT" this is NOT AN INTEGER; so therefore PDO will not run the query.

Solution

Auto Increment values simply don't need to be inserted, ignore them:

try {
    $dbh = new PDO('mysql:host=localhost;charset=utf8;dbname=database', 'user', 'password');
    $exc = $dbh->prepare("INSERT INTO fruit( type, name) VALUES ( :type, :name);");                               
    // $exc->bindParam(':id',   $fruit_object->id,   PDO::PARAM_INT);
    $exc->bindParam(':type', $fruit_object->type, PDO::PARAM_STR);
    $exc->bindParam(':name', $fruit_object->name, PDO::PARAM_STR);
    $exc->execute();
    $dbh = null;
    $exc = null;
}

---

Example of what you're trying to run:

 INSERT INTO fruit (id, type, name) VALUES (DEFAULT, 'apple', 'red apple');

But due to the security constraints of PDO (ignoring the String / Int data type issue) what is actually being run is:

INSERT INTO fruit (id, type, name) 
     VALUES ( <int var> "DEFAULT", <str var> "apple", <str var> "red apple"); 

So you're trying to insert the string variable "Default" into an integer column in MySQL

---

Answering Question 2:

  Fatal error: Uncaught Error: Cannot access private property fruit_object::$type 

This is due to your class setting the value of this type to being Private rather than Public , which means the value can not be shown outside of the class (this is a slight over simplification but time is pressing me!)

What you need to do is either:

• Set your values accessability to being public
• OR , build setter and getter methods into your class so you can whip out these private values as often as you want ( oh matron!! ).

So:

class fruit
{
    private $id;
    private $type;
    private $name;

    /***
     * Getter
     ***/ 
    function getType()
    {
        return $this->type;
    }

    /***
     * Setter
     ***/
    function setType($value){
         $this->type = $value;
    }
}

Then in your PDO:

$exc->bindParam(':type', $fruit_object->getType(), PDO::PARAM_STR);

This will output your value to the script.

If you want a much simpler approach you can simply replace private $name; with public $name; and then the named variables value will be accessible from outside the class :

 $exc->bindParam(':name', $fruit_object->name, PDO::PARAM_STR);

• Read more about Class value access levels

Answer 3

If you use (?) will be next code

$exc = $dbh->prepare("INSERT INTO fruit(id, type, name) VALUES (?, ?, ?)");                               
$exc->bindParam(1,   $fruit_object->id,   PDO::PARAM_INT);
$exc->bindParam(2, $fruit_object->type, PDO::PARAM_STR);
$exc->bindParam(3, $fruit_object->name, PDO::PARAM_STR);
$exc->execute();