Mariadb 简明教程

MariaDB - Order By Clause

如前文讨论所述， ORDER BY 子句对语句的结果进行排序。它指定所操作数据的顺序，并包括按升序 (ASC) 或降序 (DESC) 排序的选项。在忽略订单规范的情况下，默认订单为升序。

ORDER BY 子句出现在各种语句中，例如 DELETE 和 UPDATE。它们始终出现在语句的末尾，而不在子查询中或在集合函数之前，因为它们对最终结果表进行操作。您也不能使用整数来标识列。

复习以下给出的 ORDER BY 子句的一般语法 −

SELECT field, field2,... [or column] FROM table_name, table_name2,...
ORDER BY field, field2,... ASC[or DESC]

在命令提示符处或 PHP 脚本中使用 ORDER BY 子句。

The Command Prompt

在命令提示符下，只需使用标准命令 −

root@ host# mysql -u root -p password;
Enter password:*******
mysql> use PRODUCTS;
Database changed

mysql> SELECT * from products_tbl ORDER BY product_manufacturer ASC
+-------------+----------------+----------------------+
| ID_number   | Nomenclature   | product_manufacturer |
+-------------+----------------+----------------------+
| 56789       | SuperBlast 400 | LMN Corp             |
+-------------+----------------+----------------------+
| 67891       | Zoomzoom 5000  | QFT Corp             |
+-------------+----------------+----------------------+
| 12347       | Orbitron 1000  | XYZ Corp             |
+-------------+----------------+----------------------+

PHP Script Using Order By Clause

在使用 ORDER BY 子句的语句中再次使用 mysql_query() 函数 −

<?php
   $dbhost = 'localhost:3036';
   $dbuser = 'root';
   $dbpass = 'rootpassword';
   $conn = mysql_connect($dbhost, $dbuser, $dbpass);

   if(! $conn ) {
      die('Could not connect: ' . mysql_error());
   }

   $sql = 'SELECT product_id, product_name, product_manufacturer, ship_date
      FROM products_tbl ORDER BY product_manufacturer DESC';

   mysql_select_db('PRODUCTS');
   $retval = mysql_query( $sql, $conn );

   if(! $retval ) {
      die('Could not get data: ' . mysql_error());
   }

   while($row = mysql_fetch_array($retval, MYSQL_ASSOC)) {
      echo "Product ID :{$row['product_id']} <br> ".
         "Name: {$row['product_name']} <br> ".
         "Manufacturer: {$row['product_manufacturer']} <br> ".
         "Ship Date : {$row['ship_date']} <br> ".
         "--------------------------------<br>";
   }

   echo "Fetched data successfully\n";
   mysql_close($conn);
?>

当数据检索成功时，您将看到以下输出 −

Product ID: 12347
Nomenclature: Orbitron 1000
Manufacturer: XYZ Corp
Ship Date: 01/01/17
----------------------------------------------
Product ID: 67891
Nomenclature: Zoomzoom 5000
Manufacturer: QFT Corp
Ship Date: 01/01/17
----------------------------------------------
Product ID: 56789
Nomenclature: SuperBlast 400
Manufacturer: LMN Corp
Ship Date: 01/04/17
----------------------------------------------
mysql> Fetched data successfully