What is alternative to fetchall for real time loop?
Consider this:
$query = $db->prepare("SELECT * FROM record WHERE status = 0");
$query->execute();
$Record = $query->fetchall(PDO::FETCH_ASSOC);
foreach ($Record as $row) {
echo $row['name'];
sleep(5)
}
While its looping and echo'ing, I updated status = 1 from the console but it will still show the record which it shouldn't.
How about a simple fetch(): http://us3.php.net/manual/en/pdostatement.fetch.php
$query = $db->prepare("SELECT * FROM record WHERE status = 0");
$query->execute();
while ($row = $query->fetch(PDO::FETCH_ASSOC)) {
echo $row['name'];
sleep(5)
}
The results of the query are calculated once, when you run the query. If you need to get all new results with status = 0, you'll need to rerun the query.
Related
I am trying to upgrade my way to fetch data from sql from mysqli_query to fetchall.
$res = mysqli_query($db, "SELECT * FROM forum_index WHERE forum_over='yes'");
while ($arr = mysqli_fetch_assoc($res)) {
......
}
So when I use fetchAll() I'll get an array, Am I supposed to use foreach() then or is there a smarter way of doing this?
And to collect a single value from the DB this is the right way right?
$fid = (int)$_GET['id'];
$thread = $db->query("SELECT * FROM forum_threads WHERE f_id=".$fid)->fetch_array();
echo $thread['id'];
You don't need to use fetchAll() just because you're using PDO. If the query returns a large amount of data, this could slow things down because it has to collect it all into memory. You can use the same kind of loop as in your mysqli code:
$res = $pdo->query("SELECT * FROM forum_index WHERE forum_over='yes'");
while ($row = $res->fetch(PDO::FETCH_ASSOC)) {
...
}
As to your second question, you should use a parametrized query, not substitute variables.
$stmt = $pdo->prepare("SELECT * FROM forum_threads WHERE f_id= :id");
$stmt->bindParam(':id', $_GET['id']);
$stmt->execute();
while ($row = $stmt->fetch(PDO::FETCH_ASSOC)) {
...
}
Super new to PHP here, only using PHP to create my json data and having a hard time to understand the syntax. Here is some partial code:
All I am trying to do is to retrieve the value '2af8ddda-2be4-11e5-9453-b82a72d52c35' and put it in variable #sharepointID:
function selectWithSharepointID($table, $columns, $where){
try{
//Get Sharepoint file ID first
$stmt = $this->db->prepare("SELECT ID FROM table1 ORDER BY DownloadedTimeStamp DESC LIMIT 1");
$stmt->execute();
$rows = $stmt->fetchAll(PDO::FETCH_ASSOC);
//$data[] = array("ID" => $rows['ID']);
//$sharepointID = $data[0];
//$sharepointID = $rows[0];
$where = array('id'=>$sharepointID);
//$where = array('id'=>'2af8ddda-2be4-11e5-9453-b82a72d52c35'); //this works fine
...
PS: also tried to use print_r and echo but cant see anything in the console.
Thank you
You don't need to fetchAll if you only have one record. Try:
$stmt = $this->db->prepare("SELECT ID FROM table1 ORDER BY DownloadedTimeStamp DESC LIMIT 1");
$stmt->execute();
$row = $stmt->fetch(PDO::FETCH_ASSOC);
$sharepointID = $row['ID'];
If you have multiple records the fetchAll makes sense but then you iterate through that to get each row, and its values.
For a rough example where I'd use fetchAll...
$stmt = $this->db->prepare("SELECT name, userid FROM users");
$stmt->execute();
$rows = $stmt->fetchAll(PDO::FETCH_ASSOC);
foreach($rows as $row){
echo 'Name: ' . $row['name'] . ' userid :' . $row['id'];
}
This expression returns array of rows:
$stmt->fetchAll(PDO::FETCH_ASSOC);
So, you can get data from row 0 in your case:
$sharepointID = $rows[0]['ID'];
I'm in the process of updating my old mysql database techniques to prepared pdo statements. I'm all good with while loops while($row = $result->fetch()) however how would I do the following with PDO prepared statements?
$sql = "SELECT * FROM table WHERE id=".$id;
$result = mysql_query($sql) or die(mysql_error());
$loop_count = mysql_num_rows($result);
for($row=0;$row<7 && $loop_count-->0;$row++)
{
// Get next row
$loop_row = mysql_fetch_array($result);
echo $loop_row['field'];
}
I've tried this but with no joy:
$result = $conn->prepare("SELECT * FROM table WHERE id= ?");
$result->execute(array($id));
$loop_count = $result->rowCount();
for($row=0;$row<7 && $loop_count-->0;$row++)
{
// Get next row
$loop_row = $result->fetch();
echo $loop_row['field'];
}
Thanks!
UPDATE: The reason for using a for loop instead of a while loop is the ability to paginate the results, otherwise I would just put LIMIT 7 on the end of the SQL query.
To properly count rows with PDO you have to do this -
$result = $conn->prepare("SELECT * FROM table WHERE id= ?");
$result->execute(array($id));
$rows = $result->fetch(PDO::FETCH_NUM);
echo $rows[0];
But you would be better off using LIMIT in your query if all you want to do is get a static number of results.
In addition you're making your loop overly complex, there is no need to test for a range in the for condition just set the static number unless you're doing something weird, like possibly pagination.
You can try it this way:
$result = $conn->prepare("SELECT * FROM table WHERE id= ?");
$result->execute(array($id));
$loop_rows = $result->fetchAll();
$loop_count = count($loop_rows);
for($row=0;$row<7 && $loop_count-->0;$row++)
{
// Get next row
echo $loop_rows[$row]['field'];
}
As requested by the OP, here's an example of PDO prepared statements using LIMIT and OFFSET for pagination purposes. Please note i prefer to use bindValue() rather than passing parameters to execute(), but this is personal preference.
$pagesize = 7; //put this into a configuration file
$pagenumber = 3; // NOTE: ZERO BASED. First page is nr. 0.
//You get this from the $_REQUEST (aka: GET or POST)
$result = $conn->prepare("SELECT *
FROM table
WHERE id= :id
LIMIT :pagesize
OFFSET :offset");
$result->bindValue(':id', $id);
$result->bindValue(':pagesize', $pagesize);
$result->bindValue(':offset', $pagesize * $pagenumber);
$result->execute();
$rows = $result->fetchAll(PDO::FETCH_ASSOC);
This gives you the complete resultset of rows, limited to your required page. You need another query to calculate the total number of rows, of course.
What you could try is:
//Get your page number for example 2
$pagenum = 2;
//Calculate the offset
$offset = 7 * $pagenum;
//Create array
$data = array();
$result = $conn->prepare("SELECT * FROM table WHERE id= ? LIMIT 7 OFFSET ?");
$result->bind_param("ii", $id,$offset);
$result->execute();
$resultSet = $result->get_result();
while ($item = $resultSet->fetch_assoc())
{
$data[] = $item;
}
$result->close();
//echo resultSet you want
var_dump($data);
$query = "SELECT * FROM table WHERE data = '$userinput'";
$row = mysql_query($query);
while ($row = mysql_fetch_array($row))
{
echo $row['data'];
}
Ok So my questions are:
What exactly does mysql_fetch_array return?
AND if my WHERE clause finds multiple matches, shouldn't the loop execute numerous times?
I am running a program and I can only get the first result to print
You're overwriting $row. Instead use a different variable for the query result.
$query = "SELECT * FROM table WHERE data = '$userinput'";
$result = mysql_query($query);
while ($row = mysql_fetch_array($result))
{
echo $row['data'];
}
Try using mysql_fetch_assoc($row)
You should not use the same variable as the index and the loop variable.
$row = mysql_query
while( $row = ...
Replace the first $row with $result
I encounter some problem where i want to execute a SQL statement and get the total number of records + all the records.
$strSQL = "SELECT * FROM table WHERE ProjectID = 1 ";
$stmt = $db->query($strSQL);
$total = count($stmt->fetchAll());
while ($row = $stmt->fetch()){
..No More Record Shown here..
}
but there is no more record in the while loop after i execute fetchAll, i believe I need to get back to the first row or something, anyone know how to fix this?
You've already fetched all the records with fetchAll(). So when you call fetch(), there are no more records to read. Try storing the return value of fetchAll() in a variable and iterating through that. Something like this:
$strSQL = "SELECT * FROM table WHERE ProjectID = 1";
$stmt = $db->query($strSQL);
$allRows = $stmt->fetchAll();
$total = count($allRows);
foreach ($allRows as $row){
// process each $row
}