如何在PHP中自动增加mysql Limit命令

Question

i need to display mysql table rows one at a time for this i am using in php:

$result = mysqli_query($con,"select * from table limit 0,1");
while($row = mysqli_fetch_array($result)) {
    echo "First Name:" . $row['First'] . " " . "Last Name:" . $row['Last'];
    echo "<br>";
}

I need to display one row at a time, but display every new row on every php executinon, like first user gets to see first "firstname, lastname" second anonymous user on executing the page gets to see second "firstname, lastname" from the database.

this gives an error :

$result = mysqli_query($con,"select * from voucher limit '$count',1");

(i included $count to the parameters)

On execution it just displays the first row every time. I need modification to it that whenever the code is executed it returns a new row value. For example, first time it will output first row, on seond execution of the script it outputs second row and so on..

i am using php5, mysql on ubuntu server.

Please help.

Answer 1

You can do it in two ways : The first one is to save the increment value somewhere. I dont know how do you pass it or when and how you exsecute it, but it they run run separately each time (eg runs via a cron job or terminal), you can save the value in a simple file or memchache.

First way :

$offset = file_get_contents('my_counter.txt');
$offset++;
$result = mysqli_query($con,"select * from table limit " . (int) $offset . ",1");
file_put_contents('my_counter.txt', $offset);

The next one is to save the the last id from your row:

$lastID = file_get_contents('my_counter.txt');
if($lastID == "") // First call and no last id
    $lastID = 0;

$result = mysqli_query($con,"select * from table WHERE ID > " . (int) $lastID . " limit 0,1");
while($row = mysqli_fetch_array($result)) {
     echo "First Name:" . $row['First'] . " " . "Last Name:" . $row['Last'];
     $lastID = $row['ID']; // Your autoincrement row
}
file_put_contents('my_counter.txt', $lastID);

I hope I understood your question right and this helps you.

Answer 2

Try this

$result = mysqli_query($con,"select * from table ORDER BY RAND() LIMIT 1");
while($row = mysqli_fetch_array($result)) {
   echo "First Name:" . $row['First'] . " " . "Last Name:" . $row['Last'];
echo "<br>";
}

Answer 3

Since you want the data to be retrived when php code runs, you need to count the loop inside your code and increment the value like below.

If you want to loop, you need to increment the 0 in LIMIT 0,1

Something like this in a loop

LIMIT " . $loopcount . ",1
LIMIT " . $loopcount . ",1
LIMIT " . $loopcount . ",1

Im not a php programmer so i dont know the exact code.

You could if you just need a random and not the next, use SELECT * FROM table ORDER BY RAND() LIMIT 1 .

This just gives a random record, and you wont go outside of the table as it always selects one record from the table.

It will affect your performance a bit if you have a big table. But you will always get a record. If you just loop LIMIT " . $loopcount . ",1 you run the chance of trying to select outside of the table scope. If you have 100 rows, and you try LIMIT 101,1 you will get a empty recordset.