如何在 pdo 中返回 max(id) [英] How to return max(id) in pdo

问题描述

我试图返回最后一个 id 并增加它以放入 value 属性.我可以让它与旧的 mysql 一起工作，但不能与 PDO 一起工作.我正在学习(我认为)PDO，但它没有意义.

I am trying to return the last id and increment it to put in the value attribute. I can make it work with old mysql but not with the PDO. I am learning (I think) PDO but it is not making sense.

下面是代码.

    <td><label for="invNum"></label>Invoice</td>
    <?php
    $stmt = $dbconn->prepare("SELECT max(invId) FROM     invoices");
    $stmt->execute();
    $invNum = $stmt->fetch();
    
    /* mysql_select_db("customers", $dbconn);
    $result = mysql_query("SELECT max(invId) FROM   invoices");
    if (!$result) {
    die('Could not query:' . mysql_error());
    }
    $invNum = mysql_result($result, 0);*/
    ?>
    <td><input type="text" name="invNum" id="invNum" 
    size="12" value="<?php echo ++$invNum; ?>" /></td>

推荐答案

试试这个:

  $stmt = $dbconn->prepare("SELECT MAX(invId) AS max_id FROM invoices");
  $stmt -> execute();
  $invNum = $stmt -> fetch(PDO::FETCH_ASSOC);
  $max_id = $invNum['max_id'];

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