PHP mysqli bind_param type for text

Question

For a feedback form that will dump user comments into a MySQL table, I'm unsure which bind_param type to use for the user-supplied feedback text (MySQL field type = text)

function sql_ins_feedback($dtcode,$custip,$name,$email,$subject,$feedback)
{
    global $mysqli ;
    if($stmt = $mysqli->prepare("INSERT INTO feedback (dtcode,custip,name,email,subject,feedback) VALUES (?,?,?,?,?,?)")) 
    {
        $stmt->bind_param("ssssss", $dtcode,$custip,$name,$email,$subject,$feedback);
        $stmt->execute() ;
        $stmt->close() ; 
    }
}

OR THIS?

        $stmt->bind_param("sssssb", $dtcode,$custip,$name,$email,$subject,$feedback);

So, is the blob type the correct bind_param type for a text field?

What is the size limit for a bind_param("s") type?

Is there anything else one must do when using bind_param("b") ? The manual (and something else I read somewhere/sometime) suggests blob types are treated differently -- anything I should know?

Thanks

Answer 1

This actually depends on the Mysql server. The default max size for all data combined in the entire query is 1mb. See: http://dev.mysql.com/doc/refman/5.1/en/packet-too-large.html

If your data combined is under that "max_allowed_packet" threshold, just use "s" for the binding type for any text field. Infact, you can usually get away with using "s" for any field type at all (date, float, etc).

If your entire entry combined that you want to insert is over 1mb (or whatever you reset it to) in length, you'll want to use mysqli_stmt::send_long_data method and the "b" binding type to send this particular field in chunks.