我们已经看到SQL SELECT 命令从MySQLi表中获取数据.当您选择行时,MySQLi服务器可以按任何顺序自由返回它们,除非您通过说明如何对结果进行排序来指示它.但是,您可以通过添加ORDER BY子句对结果集进行排序,该子句命名要排序的列.
这是通用的SELECT命令的SQL语法和ORDER BY子句用于对MySQL表中的数据进行排序 :
SELECT field1,field2,... fieldN table_name1, table_name2 ... ORDER BY field1,[field2 ...] [ASC [DESC]]
如果提交的文件被列出,您可以对任何字段对返回的结果进行排序.
您可以在多个字段中对结果进行排序.
您可以使用关键字ASC或DESC以升序或降序获得结果.默认情况下,它是升序.
您可以通过常规方式使用WHERE ... LIKE子句来放置条件.
这将使用带有ORDER BY子句的SQL SELECT命令从MySQLi表tutorials_inf中获取数据.
尝试以下示例,该示例以降序返回结果.
root@host# mysql -u root -p password; Enter password:******* mysql> use TUTORIALS; Database changed mysql> SELECT * from tutorials_inf ORDER BY id desc; +----+-------+ | id | name | +----+-------+ | 4 | ram | | 3 | raghu | | 2 | johar | | 1 | sai | +----+-------+ 4 rows in set (0.00 sec) mysql>
确认所有ID都按降序排列.
您可以在PHP函数 mysqli_query()中使用类似ORDER BY子句的语法.此函数用于执行SQL命令,稍后可以使用另一个PHP函数 mysqli_fetch_array()来获取所有选定的数据.
试试下面的例子,它以教程作者的降序返回结果.
<?php $dbhost = 'localhost:3306'; $dbuser = 'root'; $dbpass = ''; $dbname = 'TUTORIALS'; $conn = mysqli_connect($dbhost, $dbuser, $dbpass,$dbname); if(! $conn ) { die('Could not connect: ' . mysqli_error()); } echo 'Connected successfully</br>'; $sql = 'SELECT * from tutorials_inf ORDER BY id desc'; if($result = mysqli_query($conn, $sql)){ if(mysqli_num_rows($result) > 0){ echo "<table>"; echo "<tr>"; echo "<th>id</th>"; echo "<th>name</th>"; echo "</tr>"; while($row = mysqli_fetch_array($result)){ echo "<tr>"; echo "<td>" . $row['id'] . "</td>"; echo "<td>" . $row['name'] . "</td>"; echo "</tr>"; } echo "</table>"; mysqli_free_result($result); } else { echo "No records matching your query were found."; } } else { echo "ERROR: Could not able to execute $sql. " . mysqli_error($conn); } mysqli_close($conn); ?>
示例输出应该是这样的 :
Connected successfully id name 4 ram 3 raghu 2 johar 1 sai