check if unique field exits or not

[rafal]

Hello everybody,

i try to check if the unique field inventar exists or not before i insert new record.

if the inventar exits the user should get error message.

but i dont know how to do this.

 

thank you very much for your help.

Rafal

 

here is my code

<?php
include("123.php");
$inventar = $link1->real_escape_string($_POST["inp_inventar"]);
$product = $link1->real_escape_string($_POST["inp_product"]);
$price = $link1->real_escape_string($_POST["inp_price"]);

$link1 = new mysqli("$hoster", "$nameuser", "$password", "$basedata") or die ("Connection Error!"); error_reporting (0);
$check_inventar = mysqli_query($link1, "SELECT inventar FROM products WHERE inventar='$inventar'");
$check_inventar_num = mysqli_num_rows($check_inventar);
if (isset($_POST['inp_submit']) AND $check_inventar_num = 0)
{
$query1 = "INSERT INTO products
(inventar, product, price)
VALUES ('$inventar', '$product', '$price')";
$result1 = $link1->query($query1) or die("Database Error!");
if ($result1 == true)
{
header ( 'Location:insert.php' );
}
}
else { echo "there is already product with same inventar id!"; }
mysqli_close($link1);
?>

[Barand]

Create a unique index on (product, inventor).

 

This will then give a duplicate key error if you attempt to add the same combination

 

Alternatively, having set up that index, change your query to

INSERT INTO products
(inventar, product, price)
VALUES ('$inventar', '$product', '$price')
ON DUPLICATE KEY UPDATE price = $price

which will update the existing record instead of trying to insert a duplicate

[rafal]

Thanks Barand, i made already inventor as unique key in the mysql database.

i dont want want update the price or product.

i want make insert of duplicate inventor not possible.

the user should get the following error message "there is already product with same inventor id!".

 

thanks again

Rafal

[Barand]

If you have a unique key already set on inventor then inserting a duplicate is already impossible.

[rafal]

dear Barand,

the user can not insert product if there is inventor duplicate,

my target is:

i want show the user error message if he try to insert product with duplicate inventor.

how to do this in the code?

 

thanks

Rafal

[Barand]

i want show the user error message if he try to insert product with duplicate inventor.

 

Isn't that what you are doing?

[rafal]

Hello Barand,

when i try to enter duplicate of inventor, i get the error message "Database Error!" but not what i want "there is already product with same inventor id!".

i think my "if" condition is wrong.

am i right?

[Barand]

real_escape_string() uses the database connection so you have to connect before using it

[mikosiko]

In addition to what Barand said..

You don't see anything wrong with this line in your code?

if (isset($_POST['inp_submit']) AND $check_inventar_num = 0)

 

HINT: Assignment Operator is not the same as the Comparison Operator

[rafal]

Hello Mikosiko,

i do not understand your comment.

Assignment Operator is not the same as the Comparison Operator.

what is wrong and where?

[Barand]

http://php.net/manual/en/language.operators.php