使用php pdo mysql分页

Question

我试图为一个简单的数据库表设置分页，该数据库从数据库表中选择了所有内容并将其显示在表中供用户使用，但是我一直对此有疑问。 我遵循了一个教程，该教程显示了如何设置分页，但是我仍然遇到SQLSTATE [42000]：语法错误或访问冲突：1327未声明的变量：$ startrow错误，我不确定为什么。

这是代码：

<?php

        include "db_conx.php";

            //check if the starting row variable was passed in the URL or not
if (!isset($_GET['startrow']) or !is_numeric($_GET['startrow'])) {
  //we give the value of the starting row to 0 because nothing was found in URL
  $startrow = 0;
//otherwise we take the value from the URL
} else {
  $startrow = (int)$_GET['startrow'];
}
        try {

            $db_conx = new PDO("mysql:host=$mysql_hostname;dbname=$mysql_dbname", $mysql_username, $mysql_password);

            $db_conx->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
            $stmt = $db_conx->prepare('SELECT * FROM role_type LIMIT $startrow, 3');
            $stmt->execute();
            $roles = $stmt->fetchAll(PDO::FETCH_ASSOC);
        }
        catch(Exception $e)
        {
            die ("Could not connect to the database $mysql_dbname :" . $e->getMessage());
        }
        ?>

        <h4><center>Manage Role Types</center></h4>

        <div class="container">
            <div class = "container-fluid">
                <div id = "table_container" style="width:auto; margin-top:50px;" class="mainbox col-md-6">
                    <div class="row clearfix">
                        <div class="col-md-12">
                            <table class="table table-bordered table-hover" id="tab_logic">
                                <thead>
                                    <tr >
                                        <th class="text-center">
                                            Role Type Code
                                        </th>
                                        <th class="text-center">
                                            Role Title
                                        </th>
                                    </tr>
                                </thead>
                                <tbody>
                                    <!-- populating the table with information from mysql database -->
                                    <?php foreach ($roles as $row) {
                                        echo "<tr><td>";
                                        echo $row['role_type_code'];
                                        echo "</td><td>";
                                        echo $row['role_title'];
                                        echo "</td><td>";
                                        echo '<p data-placement="top"
                                        data-toggle="tooltip"
                                        style="margin-left:5px" 
                                        title="Edit">';
                                        echo '<button class="btn btn-primary btn-xs" 
                                        data-title="Edit" 
                                        data-toggle="modal" 
                                        data-id="'; 
                                        echo $row['role_type_code']; 
                                        echo '" data-role="'; 
                                        echo $row['role_title']; 
                                        echo '" data-target="#editModal">';
                                        echo '<span class="glyphicon glyphicon-edit" />';
                                        echo '</button></p>';

                                        echo "</td>";
                                        echo "</td><td>";
                                        echo '<p data-placement="top"
                                        data-toggle="tooltip"
                                        style="margin-left:5px"
                                        title="Delete">';
                                        echo '<button class="btn btn-danger btn-xs" 
                                        data-title="Delete" 
                                        data-toggle="modal" 
                                        data-id="'; 
                                        echo $row['role_type_code']; 
                                        echo '" data-role="'; 
                                        echo $row['role_title']; 
                                        echo '" data-target="#deleteModal">';
                                        echo '<span class="glyphicon glyphicon-trash" />';
                                        echo '</button></p>';
                                        echo "</tr>"; }
                                        ?>
                                    </tbody>
                                </table>

                                <?PHP
//now this is the link..
                            echo '<a href="'.$_SERVER['PHP_SELF'].'?startrow='.($startrow+10).'">Next</a>';
                            $prev = $startrow - 10;

//only print a "Previous" link if a "Next" was clicked
                            if ($prev >= 0)
                                echo '<a href="'.$_SERVER['PHP_SELF'].'?startrow='.$prev.'">Previous</a>';
                            ?>

                            </div>
                        </div>

不知道为什么。 我尝试使用值代替变量，但是它不起作用。 任何人都知道我能克服这个问题。

谢谢

Answer 1

您不能在单引号的字符串中嵌入php变量http://php.net/language.types.string

所以你的查询是错误的

$stmt = $db_conx->prepare('SELECT * FROM role_type LIMIT $startrow, 3');

它必须是

$stmt = $db_conx->prepare("SELECT * FROM role_type LIMIT $startrow, 3");