从表中删除指定的行

Question

我有点小问题..。我正在使用PDO，我的部分代码是从数据库中的表中删除一个特定的行。我的代码如下..。

function deleteFromWorkWhere($db,$table,$user,$rowId){
        switch($table){
            case 'work':
                $tbl = 'work';
                break;
        }
        if($rowId=='all'){ // delete all records
            $sql = 'DELETE FROM '.$tbl.' WHERE username=?';  // "?"s here will get replaced with the array elements below
            $stmt = $db->prepare($sql);
            $stmt->execute(array($user)); // these array elements will replace the above "?"s in this same order
            // check for errors 
            if($stmt->errorCode() == 0) {
                // no errors, show alert and refresh page
                return '<script type="text/javascript">alert("All work history was successfully cleared!"); window.location="CV.php"; </script>';
            } else {
                // had errors
                $errors = $stmt->errorInfo();
                return '<script type="text/javascript">alert("Error deleting work history!: '.$errors[2].'"); window.location="CV.php"; </script>'; 
            }
        }
        elseif($rowId){ // delete specified row 
            $sql = 'DELETE FROM '.$tbl.' WHERE username = ? AND id = ?';  // "?"s here will get replaced with the array elements below
            $stmt = $db->prepare($sql);
            $stmt->execute(array($user,$rowId)); // these array elements will replace the above "?"s in this same order
            $affected_rows = $stmt->rowCount(); // get the number of rows affected by this change
            return $affected_rows.' row deleted.';
            // check for errors 
            if($stmt->errorCode() == 0) {
                // no errors, show alert and refresh page
                return '<script type="text/javascript">alert("Selected work history was successfully cleared!"); window.location="CV.php"; </script>';
            } else {
                // had errors
                $errors = $stmt->errorInfo();
                return '<script type="text/javascript">alert("Error deleting work history: '.$errors[2].'"); window.location="CV.php"; </script>';  
            }
        }
        else{ /// return error
        }
    }   
    if(isset($_POST['clear_work'])){
            deleteFromWorkWhere($db,'work',$_SESSION['username'],'all');    
    }
    if(isset($_POST['clear_selected_work'])){
            deleteFromWorkWhere($db,'work',$_SESSION['username']);  
    }

第一个if语句用于删除表中的所有数据和我想要使用的else，以便删除特定的行，但是它不起作用，我做错了什么？

这是按钮..。

<input type="submit" value="Clear Selected Work History" name="clear_selected_work" />

Answer 1

实际上，这里没有人能够用这里显示的代码来回答这个问题。但是，“超级特劳”和“吞咽快篮”几乎都做到了这一点。当我最初为您编写函数时，您的表单允许用户向数据库添加记录，并有一个按钮“清除所有工作历史记录”，但没有删除单个记录的方法。

我写这个函数是为了：

• 将字符串值'all'作为$rowId参数传递将删除所有记录(这是应用程序所需的)。
• 将数据库行id作为$rowId参数传递将只删除该特定行(当时不需要，但添加它是有意义的)

因为当时只有一个按钮可以删除所有内容，所以我只使用以下检查来实现：

if(isset($_POST['clear_work'])){
        // see explanation of params in function declaration above for `deleteFromWhere()`
        deleteFromWhere($db,'work',$_SESSION['username'],'all');    
}

如果要删除特定的记录，则需要做两件事：

在第一页上添加一个按钮或类似的按钮，以删除单个记录。

<form action="addCV.php" method="post"> 
    <input type="hidden" value="12345" name="clear_this_work" /><!--you'll need to set the value here to the database row id of the currently displayed record -->                  
    <input type="submit" value="Clear This Work Record" style="border: 1px solid #006; color:#F87F25; font: bold 16px Tahoma; border-radius:7px; padding:4px; background:#ffffff;"/>
</form> 

在第二页中添加检查，查看是否按下此按钮，并调用传递提供的id的函数。

if(isset($_POST['clear_this_work'])){
        // see explanination of params in function declaration above for `deleteFromWhere()`
        deleteFromWhere($db,'work',$_SESSION['username'],$_POST['clear_this_work']);    
}   

最后修正的php：

// a function that deletes records 
// $table is the table to delete from
// $user is the current username
// $rowId is the row id of the record to be deleted
// if $rowId is passed as the string "all", 
// all matching records will be deleted 
function deleteFromWhere($db,$table,$user,$rowId){
    // PDO will sanitize most vars automatically
    // however Table and Column names cannot be replaced by parameters in PDO. 
    // In this case we will simply want to filter and sanitize the data manually.
    // By leaving no default case or using a default case that returns an error message you ensure that only values that you want used get used.
    // http://stackoverflow.com/questions/182287/can-php-pdo-statements-accept-the-table-name-as-parameter
    switch($table){
        case 'work':
            $tbl = 'work'; // add more here when you want to start deleting from other tables
            break;
    }
    if($rowId=='all'){ // delete all records
        $sql = 'DELETE FROM '.$tbl.' WHERE username=?';  // "?"s here will get replaced with the array elements below
        $stmt = $db->prepare($sql);
        $stmt->execute(array($user)); // these array elements will replace the above "?"s in this same order
        // check for errors 
        if($stmt->errorCode() == 0) {
            // no errors, show alert and refresh page
            return '<script type="text/javascript">alert("All work history was successfully cleared!"); window.location="addCV.php"; </script>';
        } else {
            // had errors
            $errors = $stmt->errorInfo();
            return '<script type="text/javascript">alert("Error deleting work history!: '.$errors[2].'"); window.location="addCV.php"; </script>';  
        }
    }
    elseif($rowId){ // delete specified row 
        $sql = 'DELETE FROM '.$tbl.' WHERE username = ? AND id = ?';  // "?"s here will get replaced with the array elements below
        $stmt = $db->prepare($sql);
        $stmt->execute(array($user,$rowId)); // these array elements will replace the above "?"s in this same order
        $affected_rows = $stmt->rowCount(); // get the number of rows affected by this change
        return $affected_rows.' row deleted.';
        // check for errors 
        if($stmt->errorCode() == 0) {
            // no errors, show alert and refresh page
            return '<script type="text/javascript">alert("Selected work history was successfully cleared!"); window.location="addCV.php"; </script>';
        } else {
            // had errors
            $errors = $stmt->errorInfo();
            return '<script type="text/javascript">alert("Error deleting work history: '.$errors[2].'"); window.location="addCV.php"; </script>';   
        }
    }
    else{ /// return error
    }
}   


if(isset($_POST['clear_work'])){
        // see explanation of params in function declaration above for `deleteFromWhere()`
        deleteFromWhere($db,'work',$_SESSION['username'],'all');    
}

// add the below check 
if(isset($_POST['clear_this_work'])){
        // see explanination of params in function declaration above for `deleteFromWhere()`
        deleteFromWhere($db,'work',$_SESSION['username'],$_POST['clear_this_work']);    
}   

HTML：

<form action="addCV.php" method="post">                         
    <input type="submit" value="Clear All Work History" name="clear_work" style="border: 1px solid #006; color:#F87F25; font: bold 16px Tahoma; border-radius:7px; padding:4px; background:#ffffff;"/>
</form> 
<!--  add the below -->
<form action="addCV.php" method="post"> 
    <input type="hidden" value="12345" name="clear_this_work" /><!--you'll need to set the value here to the database row id of the currently displayed record -->                  
    <input type="submit" value="Clear This Work Record" style="border: 1px solid #006; color:#F87F25; font: bold 16px Tahoma; border-radius:7px; padding:4px; background:#ffffff;"/>
</form>