<Previous Next> Record

[astralweeks]

Hello again,

I have PHP code that displays a list of records and when you click on the title it displays details for that record. My question is, how do I add a Next / Previous record feature so the user doesn't have to hit the back key to go back to the list and select another record to display ?

[tommynanda]

whats the structure of your records? are they retrieved from database? need more description...

[astralweeks]

Yes they are in a mysql database

[LordShryku]

Is there maybe like an auto-increment field so you could select min(field) where field is greater than the current?

[tommynanda]

Lets make up a database records like this

id -|- Record det1 -|- Record det2
1 kjdsfkl lkl;k;dsf
2 kjsdfklj ikjsaldkjf
3 ksdjfl ksjdflksd

and say getit.php is our file

<?php
$id = $_GET['id'];
// Retrieve your record according to id
// Display Record

// Links
$query = "SELECT id FROM records WHERE id < $id ORDERBY DESC LIMIT 1"  // For Previous
$result = mysql_query($query)
$rowp = mysql_result($result,0); // $rowp has Previous record id
$query2 = "SELECT id FROM records WHERE id > $id ORDERBY ASC LIMIT 1" // For next Record
?>
<a href="getit.php?id=<? echo "$rowp"; ?>">Previous Record</a>

Same thing applies for next record.. execute query2 and u get next record id

NOTE: the id column should be auto-increment

Good Luck
TommYNandA

[astralweeks]

Thanks tommynanda...I will let you all know once I try it out.

Regards

[astralweeks]

I get the following error:

Warning: mysql_result(): supplied argument is not a valid MySQL result resource in ...

[LordShryku]

Which means there's an error with the sql or the connection. If you used his exact script, ORDERBY should be two words: ORDER BY.

[astralweeks]

I confirmed that the connection was made and I did not use the Order By....just LIMIT 1

[LordShryku]

Then it's going to be your sql query. Use [man]mysql_error[/man].

[astralweeks]

I figured out the error and got it working. However, regardless of the "id" being retrieved by GET, $rowp always gets a value of 1. Though my ID is auto-increment, this is a subselect of another search so the ID values can be 4, 17, 19 , 42 etc. as opposed to sequential 1,2,3,4. Does that make a difference in the recommended code ?

[Davy]

(assuming your ordered by ID number)

Can you not just have the link take the ID in a variable and do:

$varNew = $varOld + 1;

That way no matter where you are, the link will always go tot he next one.

If you're not ordering by ID nor any other integer then I'm sorry then I cannot help.

Tip: If you want to make the integer orderin ascending or descending -- use an IF statement within the link as I described above.

Note: This is not valid code

if $order == "a" then  //checking if the ordering is ascending: 1, 2, 3.
Next does this: $varNew = $varOld + 1
Previous does this: $varNew = $varOld - 1

ElseIf $order == "d" then //checking to see if order is descending: 3, 2, 1.
//The same happens if ordered descending. This will happen if the $order is NOT ascending but DESCENDING.

Next does this: $varNew = $varOld - 1
Previous does this: $varNew = $varOld + 1

Else  //This would be the 'default' order setting or if it's ordered by another column. 
[ENTER text here to order using other means.]

Wow that was messy but I hope you understood it.

[astralweeks]

Davy,

If the selected records have the ID of 5, 14 & 20 and the GET statement gets a 14, then $varNew = $varOld + 1; would return a 15 which won't exist. Correct ? Is there a command equivalent to "next record" as opposed to next sequential number ?

[Davy]

I don't know about doing it straight through MySQL as saying to the server "Ok I have this ID number of 14, give me the next number in ascending order that is valid"

I have found one function from the manual doing a search and if you can put the IDs into an array then use the next() function

EDIT: I've just spent 5 minutes searchign through the documentation for PHP and found the following:

To fetch the rows and put them into an array like I mentioned in above paragraph/s, use the mysql_fetch_array
mysqli_next_result