如何在php中获取特定值的行数[重复]

Question

This question already has an answer here:

• How to use count and group by at the same select statement 11 answers

In my database table, there are many students from different classes. I want to get the number of students in each class in a table. How can I get this and insert into a table? Here is my code:

        <?php

        function showSearchResult()
        {
            require_once('config.php');
            connect_db(); 
            $class = '';
            $result = mysql_query("SELECT * FROM ipsc_student WHERE class=2");
            $num_rows = mysql_num_rows($result);
            $rt = "";
            $rt.="<div align='center'>
                        <h1>Report IPSC</h1>
                </div>";
            $rt.= "<table width='1000' align='center' border= '1'>";
            $rt.= "<tr><td><b>SL</b></td>
                    <td><b>Class</b></td>
                    <td><b>Total Student</b></td>
                    </tr>";
            for($i =1; $i < 13; $i++){
                $rt.="<tr>";
                $rt.="<td>$i.</td>";
                $rt.="<td>$i</td>";
                $rt.="<td>$num_rows</td>";
                $rt.="</tr>";
            } 
        echo $rt;
        }
        showSearchResult();
        ?>

</div>

Answer 1

You can do group by class on your student table

SELECT `class`, COUNT(`student`) AS total_student FROM `ipsc_student` GROUP BY `class`