php - 我们可以在分页中使用 count(*) 而不是使用 count 来获取表中的记录数吗？

Question

下面是代码，这里我使用了“select count(*) from departments”而不是“select * from departments”，所以这段代码哪里错了。谁能帮我解决一下..

$num_rec_per_page=5;
    if (isset($_GET["page"])) { 
        $page  = $_GET["page"]; 
    } else { 
        $page=1; 
    }; 
    $start_from = ($page-1) * $num_rec_per_page; 
    $sql_query =  "SELECT * FROM departments LIMIT $start_from, $num_rec_per_page";
        $result = $db_connection->query($sql_query);
        if($result->num_rows > 0){
            while($rows = $result->fetch_assoc()){
                 echo "<tr>";
                 echo "<td>".$rows["id"]."<td>";
                 echo "<td>".$rows["name"]."<td>";
                 echo "<tr>";
            }
        }
        $sql = "SELECT count(*) FROM departments";  //select query for total records
        $rs_result = $db_connection->query($sql); //run the query
        $total_records =$rs_result->num_rows;  //count number of records
        $total_pages = ceil($total_records / $num_rec_per_page); 

        echo "<a href='index.php?page=1'>".'|<'."</a> "; // Goto 1st page  

        for ($i=1; $i<=$total_pages; $i++) { 
            echo "<a href='index.php?page=".$i."'>".$i."</a> "; 
        }; 
        echo "<a href='index.php?page=$total_pages'>".'>|'."</a> ";

Answer 1

我认为您唯一的问题是您尝试获取记录总数的方式。设置 SQL 查询以进行计数，然后通过读取返回的唯一行来检索它:

$sql = "SELECT count(*) AS total_records FROM departments";
$rs_result = $db_connection->query($sql);
$total_records = $rs_result->fetch_assoc()['total_records'];