MariaDB - Order BY 子句

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  简述

  正如前面讨论中提到的，ORDER BY 子句对语句的结果进行排序它指定操作数据的顺序，并包括按升序 (ASC) 或降序 (DESC) 排序的选项。省略顺序指定时，默认顺序为升序。

  ORDER BY 子句出现在各种语句中，例如 DELETE 和 UPDATE。它们总是出现在语句的末尾，而不是在子查询中或集合函数之前，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。

  查看下面给出的 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]
  

  在命令提示符或 PHP 脚本中使用 ORDER BY 子句。
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  命令提示符

  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             |
  +-------------+----------------+----------------------+
  

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  使用 Order By 子句的 PHP 脚本

  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);
  ?>
  

  成功检索数据后，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