PHP Class Database Connection Scope Issue

Question

For a new project that I'm doing in PHP I've created an SQLMethods class to connect to the database and perform queries. Tonight was the first night that I actually got to test it (I wrote it a week or so ago and forgot about it) and an unexpected error occured: When it was calling my ExecuteQuery() function, it wouldn't use the database I selected in the constructor.

The constructor:

    public function SQLMethods() {
        $SQLConnection = mysql_connect($SQLDBAddress, $SQLUserName, $SQLPassword);

        if (!$SQLConnection) {
            die('Could not connect: ' . mysql_error());
        }

        mysql_select_db($SQLDB, $SQLConnection);
    }

The function in question:

    public function ExecuteQuery($Query) {
        mysql_query($Query, $SQLConnection) or die('Could not perform query: ' . mysql_error());
    }

Does anyone see what the issue might be? Does the connection close after the constructor completes?

cruizer · Accepted Answer · 2008-09-26 10:07:49Z

7

you should declare $SQLConnection in your class, and you should refer to it as

 $this->SQLConnection

and not simply $SQLConnection.

answered Sep 26, 2008 at 10:07

cruizer

6,1512 gold badges30 silver badges34 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

mskfisher · Accepted Answer · 2011-11-08 21:06:15Z

2

$SQLConnection doesn't exist within the ExecuteQuery method.

You can either pass it directly as a parameter to ExecuteQuery, or add an sqlConnection class property that is set in the constructor and accessed as $this->sqlConnection inside your class methods.

edited Nov 8, 2011 at 21:06

mskfisher

3,4124 gold badges38 silver badges50 bronze badges

answered Sep 26, 2008 at 10:07

Greg

10.4k1 gold badge28 silver badges36 bronze badges

Comments

A J · Accepted Answer · 2016-01-22 11:09:10Z

1

The variable $SQLConnection ExecuteQuery() is trying to use is created within another scope. (The SQLMethods function).

The connection closes when the PHP script has done its work or if you close it yourself (if the connection is made within that script)

You should skip the $SQLConnection variable within ExecuteQuery as stated by the php.net documentation

If the link identifier is not specified, the last link opened by mysql_connect() is assumed.

edited Jan 22, 2016 at 11:09

A J

4,01214 gold badges40 silver badges55 bronze badges

answered Sep 26, 2008 at 10:10

Ólafur Waage

70.3k22 gold badges147 silver badges199 bronze badges

Collectives™ on Stack Overflow

PHP Class Database Connection Scope Issue

3 Answers 3

Comments

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related