How can I use mysqli_fetch_array() twice? - php

Question

I am using the entries from a database to fill a row and a column in a table. But I cannot access the SQL returned data twice using mysqli_fetch_array() twice. I need to loop mysqli result more than once. This doesn't work:
//Copy the result
$db_res = mysqli_query( $db_link, $sql );
$db_res2=$db_res;
//Top row
while ($row = mysqli_fetch_array( $db_res, MYSQL_ASSOC))
{
echo "<td>". $row['Title'] . "</td>";
}
//leftmost column
while ($row = mysqli_fetch_array( $db_res2, MYSQL_ASSOC))
{
echo "<tr>";
echo "<td>". $row['Title'] . "</td>";
.....
echo "</tr>";
}
How can I apply mysqli_fetch_array twice on the same result?

Answer 1

You should always separate data manipulations from output.
Select your data first:
$db_res = mysqli_query( $db_link, $sql );
$data = array();
while ($row = mysqli_fetch_assoc($db_res))
{
$data[] = $row;
}
Note that since PHP 5.3 you can use fetch_all() instead of the explicit loop:
$db_res = mysqli_query( $db_link, $sql );
$data = $db_res->fetch_all(MYSQLI_ASSOC);
Then use it as many times as you wish:
//Top row
foreach ($data as $row)
{
echo "<td>". $row['Title'] . "</td>";
}
//leftmost column
foreach ($data as $row)
{
echo "<tr>";
echo "<td>". $row['Title'] . "</td>";
.....
echo "</tr>";
}

Answer 2

Yes. mysqli_fetch_array() moves the pointer forward each time you call it. You need mysqli_data_seek() to set the pointer back to the start and then call mysqli_fetch_array() again.
So before calling the function a second time, do:
mysqli_data_seek($db_res, 0);

Answer 3

You don't need the while loop and you don't need to use mysqli_fetch_array() at all!
You can simply loop on the mysqli_result object itself many times. It implements Traversable interface that allows it to be used in foreach.
//Top row
foreach($db_res as $row) {
echo "<td>". $row['Title'] . "</td>";
}
//leftmost column
foreach($db_res as $row) {
echo "<tr>";
echo "<td>". $row['Title'] . "</td>";
.....
echo "</tr>";
}
However, you should separate your DB logic from your display logic and to achieve this it is best to use fetch_all(MYSQLI_ASSOC) in your DB logic to retrieve all records into an array.
If you fetch all the data into an array, you can loop that array as many times as you want.
$data = $db_res->fetch_all(MYSQLI_ASSOC);
foreach($data as $row) {
// logic here...
}

Answer 4

$squery = mysqli_query($con,"SELECT * FROM table");
while($s = mysqli_fetch_array($query)){
....
}
// add this line
mysqli_data_seek( $query, 0 );
while($r = mysqli_fetch_array($query)){
...
}
try it.....