Flagging last overall row in MySQL query using LIMIT - php

I am retrieving results from a database in batches of 5, each time taking the last 'id' and returning it via jquery so only rows with smaller 'id' are returned. I have a load more button which should disappear after all rows are loaded, even if that means 5, 7 or 11 rows.
I have this query:
$query = $pdo->prepare("SELECT * FROM names WHERE id < ? ORDER BY id DESC LIMIT 5");
$query->execute([$_POST["id"]]);
while($row = $query -> fetch()) {
echo "<div id="$row["id"].">".$row["name"]."</div>";
});
The question is, is there an easy and performant way to add a column to flag each row if it's last or not in a single query? Considering I am using LIMIT of 5, obviously the query should also check the potential existence of 5+1 row.

Set the limit to 6 and check the number of returned rows.
for the while loop, use a counter:
$query = $pdo->prepare("SELECT * FROM names WHERE id < ? ORDER BY id DESC LIMIT 6");
$query->execute([$_POST["id"]]);
$n=5;
while($row = $query -> fetch() && $n-->0)
{
echo "<div id="$row["id"].">".$row["name"]."</div>";
}

Related

PHP and MYSQL get random row in table

Hello I have the following code which returns the amount of rows in a table and the picks a random number between 1 and the amount of rows. I want to be able to get the row in the MySQL table that corresponds to the random number. So if the number is two, I want to get the second row down.
Here is my code so far:
$query = mysql_query("SELECT count(*) as total from videos");
$result = mysql_fetch_array($query);
$TotalCount = $result['total'];
$RandRow = mt_rand(1,$TotalCount);
I do have a id column but all the id's are not in order it goes like this for example: 4, 27, 43, 2, 18, 109, So i cant use that. How can I get a row in a table that corresponds to my random number?
You want one random row out of your table, right? Then you could use ORDER BY RAND() in your query and LIMIT 1. It sorts - surprise - randomly and only returns one dataset.
e.g.
$query = mysql_query("SELECT * FROM videos ORDER BY RAND() LIMIT 1");
So you just have to do one query.
$query = mysql_query("SELECT id from videos");
$ids = array()
While($row=mysql_fetch_array($query)){
$ids[] =$row['id']
}
$RandRow = array_rand($ids,1);
You can fetch all rows ids as an array and select a random one from array by array_rand

How do I find the last record my database table using PDO?

How can I execute this using PDO? I use MySQL for my database. I am trying to call the last infog_id.
$q = $conn->query("SELECT * FROM Infographic ORDER BY infog_id DESC LIMIT 1");
$q->fetchAll();
Similar to what Sean said, if you only need one column, don't get all of them.
$q = $conn->query("SELECT infog_id FROM Infographic ORDER BY infog_id DESC LIMIT 1");
$infog_id = $q->fetchColumn();
fetchColumn() by default retrieves the first column from the next available row, for this query, this will be infog_id.
If you actually want the whole row, use fetch().
$q = $conn->query("SELECT * FROM Infographic ORDER BY infog_id DESC LIMIT 1");
$row = $q->fetch();
fetch() returns the next available row, in this case, there is only one (LIMIT 1).

Random data mysql

I have table in mysqli database now i want to get 1 result random
This is code mysql
$cid = $_GET['id'];
$ans = $db->query("select * from result where cat_id='$cid' limit 1");
$rowans = $ans->fetch_object();
echo"
<h4>".$rowans->title."</h4><br>
<img src='".$rowans->img."' style='width:400px;height:300;' />
<p>".$rowans->desc."</p>";
in this code i get 1 result but not random always gives me the same result
SQL:
SELECT *
FROM result
ORDER BY rand()
LIMIT 1
LIMIT orders the rows by the primary key of the table, so you always get the same one (the "first" row according to that key).
Try:
SELECT * FROM result WHERE cat_id='$cid' ORDER BY RAND() LIMIT 0,1;
You can think of it this way: it first orders the results by a random order, then picks the first one.

show 2 random rows instead of one

MY SQL QUERY:
$q = mysql_query("SELECT * FROM `ads` WHERE keywords LIKE '%$key%' ORDER BY RAND()");
RESULTS: KEYWORD123
This query searches and results in one random row but i want to show 2 random rows.
How to do that?
any solution?
how??
im grabbing it using this
$row = mysql_fetch_array($q); if ($row
<= 0){ echo 'Not found'; }else{ echo
$row['tab']; }
That query (as-is) will return more than one row (assuming more than one row is LIKE %$key%). If you're only seeing one record, it's possible you're not cycling through the result set, but rather pulling the top response off the stack in your PHP code.
To limit the response to 2 records, you would append LIMIT 2 onto the end of the query. Otherwise, you'll get every row that matches the LIKE operator.
//Build Our Query
$sql = sprintf("SELECT tab
FROM ads
WHERE keyword LIKE '%s'
ORDER BY RAND()
LIMIT 2", ('%'.$key.'%'));
// Load results of query up into a variable
$results = mysql_query($sql);
// Cycle through each returned record
while ( $row = mysql_fetch_array($result) ) {
// do something with $row
echo $row['tab'];
}
The while-loop will run once per returned row. Each time it runs, the $row array inside will represent the current record being accessed. The above example will echo the values stored in your tab field within your db-table.
Remove your order by and add a LIMIT 2
That happens after the execution of the SQL.
Right now you must be doing something like
$res = mysql_query($q);
$r = mysql_fetch_array($res);
echo $r['keywords'];
what you need to do
$q = mysql_query("SELECT * FROM ads WHERE keywords LIKE '%$key%' ORDER BY RAND() LIMIT 2");
$res = mysql_query($q);
while($r = mysql_fetch_array($res)){
echo "<br>" . $r['keywords'];
}
Hope that helps
This query will return all rows containing $key; if it returns only one now this is simply by accident.
You want to add a LIMIT clause to your query, cf http://dev.mysql.com/doc/refman/5.0/en/select.html
Btw both LIKE '%... and ORDER BY RAND() are performance killers

How do I fetch the last record in a MySQL database table using PHP?

I want to fetch the last result in MySQL database table using PHP. How would I go about doing this?
I have 2 Columns in the Table, MessageID(auto) & Message.
I already know how to connect to the database.
Use mysql_query:
<?php
$result = mysql_query('SELECT t.messageid, t.message
FROM TABLE t
ORDER BY t.messageid DESC
LIMIT 1') or die('Invalid query: ' . mysql_error());
//print values to screen
while ($row = mysql_fetch_assoc($result)) {
echo $row['messageid'];
echo $row['message'];
}
// Free the resources associated with the result set
// This is done automatically at the end of the script
mysql_free_result($result);
?>
The SQL query:
SELECT t.messageid, t.message
FROM TABLE t
ORDER BY t.messageid DESC
LIMIT 1
...uses the ORDER BY to set the values so the highest value is the first row in the resultset. The LIMIT says that of all those rows, only the first is actually returned in the resultset. Because messageid is auto-increment, the highest value is the most recent one...
Records in a relational database do not have an intrinsic "order" so you cannot fetch the "last" record without some kind of ORDER BY clause.
Therefore, in order to fetch the "last" record, simply reverse the ORDER BY clause (change ASC to DESC or vice versa) then select the first result.
If you have an auto-increment field and you just want to find the last value that was inserted, you can use the fact that the auto-increment fields are ever-increasing (therefore the "last" one will be the one with the highest value) and do something like this:
SELECT *
FROM my_table
ORDER BY id_field DESC
LIMIT 1
Of course you can select the last row by sorting DESC in your query. But what if you want to select the first row and then the last. You can run a new query, but you can also use the function mysql_data_seek. check code below:
$result = mysql_query('YOUR QUERY') or die('Invalid query: ' . mysql_error());
$row_first = mysql_fetch_array($result);
mysql_data_seek($result , (mysql_num_rows($result)-1));
$row_last = mysql_fetch_array($result);
Hope this helps
The MySql query would look like this:
select MessageID, Message
from Table
order by MessageID desc
limit 1;
I am too rusty with PHP to give you the right syntax for executing this.
This query works because you have an auto-incrementing identifying field (MessageID). By ordering the results by that field in descending (largest to smallest) order we are effectively returning the records in the table in reverse order. The limit 1 clause simply limits the result set to one record - the last one in the table.
What do you mean by "the last result"? You need to precise a bit more.
Do you mean "the last entry I registered"?
In this case you should use the appropriate method (depending on the extension you are using) mysqli->insert_id OR mysql_insert_id.
If you mean "the latest entry in the table", an SQL query such as Andrew Hare's is just what you need.
Do you mean the last record or do you need the id of the most recently inserted record? For that you would use the PHP mysql_insert_id() function. Or if you are using the myusqli extension use $mysqli->insert_id.
for some reason (which I don't know why), my boss force me to get the data in this way:
$message_arr = array();
while ($row = mysql_fetch_assoc($result)) {
$message_arr['messageid']= $row['messageid'];
$message_arr['message']= $row['message'];
}
return $message_arr;
Of course, you need everything from OMG Ponies's answer I'm just telling you another way to do it =)
I hope this help.
You should use SELECT query. How SELECT works.
SELECT * FROM table - selects everything in a table (id, row 1, row 2,...)
SELECT id FROM table - selects only particular row from table.
If you now know, how to select, you can use additional logic.
SELECT * FROM table ORDER by id DESC LIMIT 1;
selects everything from table table, orders it by id - orders it DESCENDING and limits the query to only one result.
If you would do it like this:
SELECT * FROM table ORDER by id ASC limit 1; - you would get 1 entry into database.
You can order it by any row you want.
Hope it helps.
One thing to remember is that data does not get saved in the insertion order in any MYSQL database. So in order to get the last entered record u will have to have an auto increment field. Since there is an auto increment field in this table we are good to go.
The below script will help to get the last entered record
<?php
$sql = "SELECT * FROM table_name ORDER BY MessageID DESC LIMIT 2";
$result_set = mysql_query($sql);
if($result_set){
while($row = mysql_fetch_array($result_set)) {
echo "Message Id: ".$row['MessageID']."<br>";
echo "Message: ".$row['Message']."<br>";
}
//creating alert
echo "<script type=\"text/javascript\">alert('Data was Retrieved
successfully');</script>";
}
else{
//creating alert
echo "<script type=\"text/javascript\">alert('ERROR! Could Not Retrieve
Data');</script>";
}
?>
The query selects all the records in the table and orders them according to the descending order of the MessageID (as it is the auto increment field) and limits the returned result to only one record. So since the table is ordered according to the descending order of the MessageID only the last entered record will be returned.
NOTE: if you are using a newer version you will have to use mysqli_query($connection_variable,$sql); instead of mysql_query($sql); and mysqli_fetch_array($result_set) instead of mysql_fetch_array($result_set)
$result = mysql_query('select max(id) from your_table ') or die('Invalid query: ' . mysql_error());
while ($row = mysql_fetch_assoc($result)) {
echo $row['id'];
echo $row['message'];
}
//
//
mysql_free_result($result);
simple like that
this code of php works fine
SELECT t.messageid, t.message
FROM TABLE t
ORDER BY t.messageid DESC
LIMIT 1
if you don't have concurrent entries going into some table.b'cause concurrent entries may not go in accordance of their insertion order.
$statement = $PDO->prepare("
SELECT MessageID,
Message
FROM myTable
ORDER BY MessageID DESC
LIMIT 1;
");
$statement->execute();
$result = $statement->fetch(\PDO::FETCH_ASSOC);
echo $result['MessageID']." and ".$result['Message'];

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