SubSelect或SubQuery

Question

Below will successfully find the product a customer has submitted * http://inks-etc.com/Canon/canon_inkdesign.php?ID=114 The ID=114 came from the $_GET['ID'] and when into the SELECT to receive the products: Price, Product No., Description, Image. Now I have been trying to get about 4 (LIMIT 4) more similar products to capture of the left side of the page so if the customer chooses a LC41 Black, I can provide LC41 Cyan, LC41 Magenta, LC41 Yellow as well. I am thinking the 'SELECT Sub query' would be helpful. Will you tell me what I must modify and even begin again to perform this task.

    $inksetc = htmlentities($_GET['ID']);

     $sql2 = "SELECT Id,   Product_Type,  Product_No ,  miniImageFarm

         FROM `Canon_INK`

         WHERE IN
             (SELECT Id= $inksetc FROM Canon_INK WHERE Id LIKE $inksetc) 

         LIMIT 4";

$result = mysqli_query($dbc,$sql2) or die(mysqli_error($dbc));

    while($rows = mysqli_fetch_array($result)){
?>

Answer 1

You don't need a sub-query for this and you need wildcard '%' so that you could search by pattern and your $sql2 should look like this therefore:

$sql2 = "SELECT Id,   Product_Type,  Product_No ,  miniImageFarm ";
$sql2 .= "FROM `Canon_INK` ";
$sql2 .= "WHERE Id LIKE '%".SUBSTR($inksetc,0,4)."%'";

I added for % for matching search.

Answer 2

I believe you want something like this:

SELECT Id, Product_Type, Product_No, miniImageFar
FROM Canon_INK
WHERE SUBSTR(Id, 0, 4) = SUBSTR($inksetc, 0, 4)

Read up on the LIKE operator; it does not say one string is like another, but rather that a string matches a pattern.

Answer 3

$inksetc = htmlentities($_GET['ID']);// need to store LC41 in $_GET['ID'].

  $sql2 = "SELECT Id,   Product_Type,  Product_No ,  miniImageFarm

     FROM `Canon_INK`

     WHERE Id IN
         (SELECT Id FROM Canon_INK WHERE Id LIKE '%".$inksetc."%') // use Id instead of Id= $inksetc.

     LIMIT 4";

$result = mysqli_query($dbc,$sql2) or die(mysqli_error($dbc));

 while($rows = mysqli_fetch_array($result)){

?>

Answer 4

I'm assuming that the "LC41 Black" type value is stored in the Product_No column - not the Id column. I'm also assuming that you don't want the original product to show up in the list of similar products.

You can therefore join the table with itself to get the results, rather than using a subquery:

SELECT  c.Id,  c.Product_Type,  c.Product_No,  c.miniImageFarm
FROM Canon_INK AS c
INNER JOIN 
    Canon_INK AS OriginalProduct
ON 
    SUBSTR(c.Product_No, 0, 4) = SUBSTR(OriginalProduct.Product_No, 0, 4)
AND
    c.Id != OriginalProduct.Id
WHERE
    OriginalProduct.Id = $intsect
LIMIT 4;

Your query is insecure at the moment - please do not escape things for SQL using the htmlentities function, instead have a look at mysqli_real_escape_string .