Php PDO:未选择任何数据库

以下是按顺序排列的文本：

登录->选择数据库->从给定卡片列表中选择->mysql流程生成测试列表->选择测试->mysql流程根据所选卡片和测试生成批次号

一个脚本“mysql进程生成测试列表”正在运行，我可以选择其中一个测试

然后，弹出错误消息“SQLSTATE[3D000]：无效目录名：1046未选择任何数据库”的异常“PDOException”

为什么错误说明虽然已选择数据库，但未选择任何数据库

有两个php文件：

gatheretests2.php

（工作）和

gatherebatches.php

（不工作）

main.php（节选1）

gathertests2.php

<?php
    require_once($_SERVER['DOCUMENT_ROOT'] . '/firephp_include.php');
$firephp->setEnabled(TRUE);
$firephp->info('Start debugging in gathertest2.php');
require_once '../scripts/login.php';
    $db = $_POST['testDB'];
$stmt_use = $dbh->prepare("use $db");//ok
$firephp->fb($stmt_use);

    try //PDO Driver is used in PHP for working with MySQL!!!!
    {
        $stmt_use  -> execute();//ok
        $firephp->log("Successfully executed!");
    }

    catch (PDOException $err) //PDOException is declared in login.php
    {
        $alertmsg = $err->getMessage();
        include 'alertmessage.php';
        $firephp->error("Unsuccessfully executing: $err");
    }
    $stmt_call1 = $dbh->prepare('call listmfg_codes()');
$firephp->fb($stmt_call1);

    try //PDO Driver is used in PHP for working with MySQL!!!!
    {
        $stmt_call1->execute();
        $firephp->log("Successfully executed!");
    }

    catch (PDOException $err) //PDOException is declared in login.php
    {
        $alertmsg = $err->getMessage();
        include 'alertmessage.php';
        $firephp->error("Unsuccessfully executing: $err");
    }

$result = $stmt_call1->fetchAll(PDO::FETCH_ASSOC); //ok
$output = json_encode($result); 
echo $output;
$firephp -> fb($result);
$firephp -> info("End");

<?php
require_once($_SERVER['DOCUMENT_ROOT'] . '/firephp_include.php');
$firephp->setEnabled(TRUE);
$firephp->warn('Start debugging in gatherbatches.php');
require_once '../scripts/login.php';
    $card = $_POST['testCard'];//must add '' in "" bracket for call command to work
$stmt_call2 = $dbh->prepare("call listbatch('$card')");
$firephp->fb($stmt_call2);
try //PDO Driver is used in PHP for working with MySQL!!!!
    {
        $stmt_call2->execute();
        $firephp->log("Successfully executed!");
    }

catch (PDOException $err) //PDOException is declared in login.php
    {
        $alertmsg = $err->getMessage();
        include 'alertmessage.php';
        $firephp->error("Unsuccessfully executing: $err");  
        }

$result = $stmt_call2->fetchAll(PDO::FETCH_ASSOC); //ok
    $output = json_encode($result); 
echo $output;
$firephp -> fb($result);
$firephp -> warn("End");

main.php（节选2）

gatherbatches.php

<?php
    require_once($_SERVER['DOCUMENT_ROOT'] . '/firephp_include.php');
$firephp->setEnabled(TRUE);
$firephp->info('Start debugging in gathertest2.php');
require_once '../scripts/login.php';
    $db = $_POST['testDB'];
$stmt_use = $dbh->prepare("use $db");//ok
$firephp->fb($stmt_use);

    try //PDO Driver is used in PHP for working with MySQL!!!!
    {
        $stmt_use  -> execute();//ok
        $firephp->log("Successfully executed!");
    }

    catch (PDOException $err) //PDOException is declared in login.php
    {
        $alertmsg = $err->getMessage();
        include 'alertmessage.php';
        $firephp->error("Unsuccessfully executing: $err");
    }
    $stmt_call1 = $dbh->prepare('call listmfg_codes()');
$firephp->fb($stmt_call1);

    try //PDO Driver is used in PHP for working with MySQL!!!!
    {
        $stmt_call1->execute();
        $firephp->log("Successfully executed!");
    }

    catch (PDOException $err) //PDOException is declared in login.php
    {
        $alertmsg = $err->getMessage();
        include 'alertmessage.php';
        $firephp->error("Unsuccessfully executing: $err");
    }

$result = $stmt_call1->fetchAll(PDO::FETCH_ASSOC); //ok
$output = json_encode($result); 
echo $output;
$firephp -> fb($result);
$firephp -> info("End");

<?php
require_once($_SERVER['DOCUMENT_ROOT'] . '/firephp_include.php');
$firephp->setEnabled(TRUE);
$firephp->warn('Start debugging in gatherbatches.php');
require_once '../scripts/login.php';
    $card = $_POST['testCard'];//must add '' in "" bracket for call command to work
$stmt_call2 = $dbh->prepare("call listbatch('$card')");
$firephp->fb($stmt_call2);
try //PDO Driver is used in PHP for working with MySQL!!!!
    {
        $stmt_call2->execute();
        $firephp->log("Successfully executed!");
    }

catch (PDOException $err) //PDOException is declared in login.php
    {
        $alertmsg = $err->getMessage();
        include 'alertmessage.php';
        $firephp->error("Unsuccessfully executing: $err");  
        }

$result = $stmt_call2->fetchAll(PDO::FETCH_ASSOC); //ok
    $output = json_encode($result); 
echo $output;
$firephp -> fb($result);
$firephp -> warn("End");

好了，完成了。 请告诉我哪里出错了。请参阅以下附件：

//添加了login.php

<?php 
   $dsn = 'mysql:host=localhost;Port=3306';
   $user = 'root'; $pswd = '';
   $dbh = new PDO($dsn, $user, $pswd, array(PDO::ATTR_PERSISTENT, TRUE));     
   $dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);    
   $dbh->setAttribute(PDO::ATTR_EMULATE_PREPARES, false); 
  ?>

---

我没有读那么多代码，但我觉得你对PHP工作原理的看法是错误的

最有可能的情况是，您将客户机-服务器应用程序想象成一个桌面应用程序—实体和独立。这是错误的。所有这些AJAX调用都是为了分离和清理PHP实例而进行的，对以前的执行一无所知。因此，在以前的调用中选择的任何数据库在当前的调用中都没有帮助-您必须再次初始化所有资源。

还有一件非常奇怪的事情：您正在从客户端传递一个db名称！从架构和安全的角度来看，我认为这是一种奇怪的行为。此外，对于这种本地化的情况，没有一个单一的理由像几个测试那样拥有多个数据库

因此，请以常规和适当的方式：

• 使用一个数据库
• 在login.php中选择一次
• 可能会重新安排测试，使用one表保存所有类似数据

---

你永远不会有任何麻烦

您在哪里初始化了$dbh变量。。确保它看起来像$dbh=newpdo（'mysql:host=localhost；dbname='，''，PASSWORD'）$dbh变量在“../scripts/login.php”中初始化。请参阅require_once命令。因此，我能够连接到数据库，GathereTestS2.php正在工作。但是gatherbatches.php不起作用。@user1739825，在phpfire日志中显示login.phpLooking，看起来您在gathertests2.php上选择了数据库，但在gatherbatches.php中没有。您在gatheretest2.php中有“$stmt_use=$dbh->prepare（“use$db”）”语句，并且您没有在gatherebatches.php中的任何位置选择数据库，因此“$dbh->setAttribute（PDO:：ATTR_ERRMODE，PDO:：ERRMODE_EXCEPTION）；”是罪魁祸首。现在，由于没有错误，即使删除了“ATTR_ERRMODE”，也不会更新任何记录。GathereTestS2.php工作，而GathereBatch不工作。再次证明“$dbh->setAttribute（PDO:：ATTR_ERRMODE，PDO:：ERRMODE_EXCEPTION）；”与此无关。相反，似乎每次执行任何mysql脚本之前都需要指示数据库的名称。不是吗？

 DELIMITER $$
 DROP PROCEDURE IF EXISTS `testdata2060_03`.`listbatch` $$
 CREATE DEFINER=`root`@`localhost` PROCEDURE `listbatch`(mfgnum VARCHAR(24))
 BEGIN
     SELECT batch FROM test WHERE mfg_code = mfgnum group by batch order by batch desc;
 END $$
 DELIMITER ; 

<?php 
   $dsn = 'mysql:host=localhost;Port=3306';
   $user = 'root'; $pswd = '';
   $dbh = new PDO($dsn, $user, $pswd, array(PDO::ATTR_PERSISTENT, TRUE));     
   $dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);    
   $dbh->setAttribute(PDO::ATTR_EMULATE_PREPARES, false); 
  ?>