check for record before deletion

ishah

I am new to php. I need to write a statement to check for the record before it delete from the database. I know the little concept but i need the exact syntex, how to raise error if the first query is true. Will appreciate prompt response. tks

My query looks like :

<?php

// connect to the database
$dbConn = odbc_connect("abc","","")
or die("Error opening database .... use the browsers BACK button");

// store the product id from the POST
$code = $_POST["prodcode"];

// Check for record
$sqlquery = "select prodcode from prodlist where prodcode='". '$code . "'";

// OK... Delete the requested product
$sqlQuery = "DELETE FROM prodList where prodCode='" . $code . "'";

odbc_close($dbConn);
?>

thorpe

you dont really need to check if the record exists first, it just wont delete it if it doesn't (waste of resources really).

anyway... never used odbc, but it would be something like.

$sql = "select prodcode from prodlist where prodcode='$code'"; 
$result = odbc_query($sql);
if (odbc_num_rows($result) > 0) {
  $sql = "DELETE FROM prodList where prodCode='$code'";
  $result = odbc_query($sql);
  if ($result) {
    echo 'record deleted';
  }
} else {
  echo 'record not found';
}

ishah

Thanks for posting the request. One more last request. How the query will look like if I want

"don’t add a product with an existing code"

<?php

$dbConn = odbc_connect("flamingo","","")
or die("Error opening database .... use the browsers BACK button");

// store the products new details from the POST
$code = $POST["prodcode"];
$name = $POST["prodname"];
$desc = $POST["proddesc"];
$price = $POST["prodprice"];

$sqlQuery = "INSERT INTO prodlist (prodcode, prodname, proddesc, prodprice)
VALUES ('".$code."','".$name."', '".$desc."', '".$price."',)";

Tks for the precious time u gave to my query

thorpe

its very simular to the code above. just check the record exists, if it does, display your message.

come on.... you can do it :-P

ahundiak

I think what you really want to do in both cases is to check for the number of affected records using odbc_num_rows()

You can run into problems when you rely on the results of one operation for a second operation unless you do some expensive table locking.

ishah

What you suggest? advice please

ahundiak

Addressing "don’t add a product with an existing code"

Make sure you create an unique index on the product code field when you create the table.
Try inserting a new product code.
Check the return code for errors
a. No errors then all is well.

b. Duplicate record error indicates the code was already in the table
c. Other error - deal with

Consider the following scenerio:
1. Person A checks for a given product code. None is found.

Person B just happens to insert the same code.
Person A then tries to insert the same code thinking that it does not exist.

Now you may not be much time between steps 1 and 3 but in a web enviroments with multiple people hitting the databases you can easily run into hard to find errors.