Question

So i am trying to make a backup class and this is what I have so far. Issue is the $tbl_data is empty. What am I doing wrong.

The connection to the database is successful.

Without the ‘echo $tbl_data’, the ‘$current_table – current table’ output is correct but if ‘echo $tbl_data’ is used, only the first table is shown ( trying to backup two tables to begin with ).

class mBackup{

private $_connection = ""; //db connection var
private $output = ""; //sql output
private $tbl_data = "";
private $tbl_row = "";
private $nfields = "";
private $create_table_query = "";
private $create_table_output = "";

public function __construct($dbhost,$dbname,$dbuser,$dbpassword){

    $this->_connection = new mysqli($dbhost,$dbuser,$dbpassword,$dbname);

    //possible connection error
    if($this->_connection->connect_errno){
        echo "Failed to connect to the DB";
    }
    else{
        echo "Connected<br />"; 
    }
}

public function backup_db(){

    //get the table names from the DB and store in an array
    $result = $this->_connection->query("SHOW TABLES");

    //get the TABLE names
    while($row = $result->fetch_row())
    {
        $table_names[] = $row[0];
    }

    //For each table
    foreach($table_names as $current_table)
    {
        echo $current_table." - current table<br />"; //debug

        $tbl_data = "";
        $tbl_row = "";
        $nfields = "";
        $create_table_query = "";
        $create_table_output = "";

        //SELECT Everything from the table in use       
        $query = $this->_connection->prepare("SELECT * FROM ?");
        $query->bind_param('s', $current_table);
        $query->execute();
        $query->bind_result($tbl_data);
        $query->fetch();

        echo $tbl_data."<br/>";

        }
}

Answer 1

Try something like:

while ($query->fetch()) {
     echo $tbl_data;
}

and see if that gets you anything. From the little that I know, bind_result binds columns in the result set to variables. If your table has 5 columns, you should have bind_result($var1, $var2, $var3, $var4, $var5) but since your number of columns are going to change depending on the table, I don’t know if bind_result will give you what you need.

Try closing the prepared statement after every loop

$query->close();

or resetting.

$query->reset()