MySQL: Rows holding group wise maximum
Rows holding group-wise maximum
In this page, we have shown how to retrieve the rows holding group-wise maximum for a column.
In the example shown and explained in this page, we retrieved the most expensive books of each language.
Example:
Sample table: book_mast
Code:
SELECT book_name, pub_lang, book_price
FROM book_mast b1
WHERE book_price =
SELECT MAX( b2.book_price )
FROM book_mast b2
WHERE b1.pub_lang = b2.pub_lang );
Explanation:
The above MySQL statement has performed the following -
1. book_name, pub_lang, book_price are retrieved from book_mast, if
a) language of the most costly book of book_mast aliased as b2 and b1 are alike.
Sample Output:
mysql> SELECT book_name, pub_lang, book_price -> FROM book_mast b1 -> WHERE book_price = ( -> SELECT MAX( b2.book_price ) -> FROM book_mast b2 -> WHERE b1.pub_lang = b2.pub_lang ); +----------------------------------+----------+------------+ | book_name | pub_lang | book_price | +----------------------------------+----------+------------+ | Guide to Networking | Hindi | 200.00 | | Transfer of Heat and Mass | English | 250.00 | | Fundamentals of Heat | German | 112.00 | | The Experimental Analysis of Cat | French | 95.00 | +----------------------------------+----------+------------+ 4 rows in set (0.00 sec)
PHP script:
<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>example-rows-holding-group-wise-maximum-for-a-column php mysql examples | w3resource</title>
<meta name="description" content="PHP MySQL PDO Example">
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/css/bootstrap.min.css">
</head>
<body>
<div class="container">
<div class="row">
<div class="col-md-12">
<h2>List of most expensive books of each language : </h2>
<table class='table table-bordered'>
<tr>
<th>Book</th><th>Language</th><th>Price</th>
</tr>
<?php
$hostname="your_hostname";
$username="your_username";
$password="your_password";
$db = "your_dbname";
$dbh = new PDO("mysql:host=$hostname;dbname=$db", $username, $password);
foreach($dbh->query('SELECT book_name, pub_lang, book_price
FROM book_mast b1
WHERE book_price = (
SELECT MAX( b2.book_price )
FROM book_mast b2
WHERE b1.pub_lang = b2.pub_lang )') as $row) {
echo "<tr>";
echo "<td>" . $row['book_name'] . "</td>";
echo "<td>" . $row['pub_lang'] . "</td>";
echo "<td>" . $row['book_price'] . "</td>";
echo "</tr>";
}
?>
</tbody></table>
</div>
</div>
</div>
</body>
</html>
Online Practice Editor:
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- Weekly Trends and Language Statistics
- Weekly Trends and Language Statistics