Prepare statement query not executing

[shades]

Hi, 

 

Can someone point out the mistake ? I tested the query in MySQL workbench and it works fine but in the prepare statement it is not executing and also I get no error.

if(isset( $_POST['name'], $_POST['samplecount'], $_POST['decks'])) 
{  

  $name = $_POST['name'];
  $sample = $_POST['samplecount'];
  $decks = $_POST['decks'];
  $rows = ($sample/$decks);

  for ($i=0; $i<$decks; $i++){

    for ($j=1; $j<=$rows; $j++) {

         $stmt = $dbconnect -> prepare(" INSERT INTO decks (id, dnumber, vtext) 

        ( SELECT :id, :dnumber, 

        (SELECT r.vtext FROM rsample r WHERE r.groupname = :groupname  AND r.vtext 

          NOT IN (SELECT vtext FROM decks) 

        )
         ORDER BY rand() LIMIT 1
        )
    "); 

  $stmt -> bindValue(':id', $i);
  $stmt -> bindValue(':dnumber', $j);
  $stmt -> bindValue(':groupname',$name)
  $stmt -> execute ();

    }
  }
}

In my code I use name = "test" value of samplecount = 8 and decks = 2. So $rows will be 4.

My Requirement: Out of the 8 texts. I want to get the data like below and I want the texts to be in random order.

DeckId     DeckNumber   Text
D1             1         CC
D1             2         AA
D1             3         ZZ
D1             4         JJ
D2             1         FF
D2             2         BB
D2             3         CC
D2             4         WW
 

Any help will be greatly appreciated.

Thanks

[Barand]

Prepare the statement once, before the loop.

 

Inside the loop you bind the new values and execute.

[Psycho]

Running loops and doing a select statement each time [especially with rand()] is a bad idea. here is what I think is a better approach.

 

1. Run ONE SELECT query to get all of the vtext values from the rsample table for the groupname

2. Populate those results into an array

3. User array_shuffle() to randomize the results of the array

4. Run the loops for $i & $j like you have now, but create a simple INSERT statement  like this

INSERT INTO decks
    (id, dnumber, vtext) 
VALUES (:id, :dnumber, :vtext)

5. Define the vtext value on each loop using array_shift() which will remove and return the first value in the array

$stmt -> bindValue(':vtext', array_shit($vtextValuesAry));

Edited September 1, 2017 by Psycho

[shades]

 

Running loops and doing a select statement each time [especially with rand()] is a bad idea. here is what I think is a better approach.

 

1. Run ONE SELECT query to get all of the vtext values from the rsample table for the groupname

2. Populate those results into an array

3. User array_shuffle() to randomize the results of the array

4. Run the loops for $i & $j like you have now, but create a simple INSERT statement  like this

INSERT INTO decks
    (id, dnumber, vtext) 
VALUES (:id, :dnumber, :vtext)

5. Define the vtext value on each loop using array_shift() which will remove and return the first value in the array

$stmt -> bindValue(':vtext', array_shit($vtextValuesAry));

 

Thank you. The solution is perfect.