Why appending text to field replace all with 0

Question

 $invoice_id = $data['invoice_id'];
        $remark = '  ### Manually set as Paid Note: '.$data['paid_note'].' ###';
        $sql = "UPDATE tbl_invoice SET payment_status = 1, remark = remark+'$remark' WHERE invoice_id = $invoice_id";

This should append 'remark' field with new value. but remark field is updated with '0'. Strange! Can't find out whats problem is going on my code. Any idea?

NB: I am using MySql DBMS.

Answer 1

You should learn to use parameters. But your issue is using + , which is addition. I presume you want string concatenation:

UPDATE tbl_invoice
    SET payment_status = 1,
        remark = CONCAT(remark, '$remark')
    WHERE invoice_id = $invoice_id;

However, the code should look more like this:

UPDATE tbl_invoice
    SET payment_status = 1,
        remark = CONCAT(remark, ?)
    WHERE invoice_id = ?;

where ? is a placeholder for the parameters.