使用PHP获取添加文件的ID

将下表命名为FileContent

ID  |  version  |  fileContent  | ownerID

我需要获得用户通过POST请求添加的文件的ID，然后我必须对其进行处理。你能帮我解决这个问题吗

if($_POST) {
    $name = mysqli_real_escape_string($connection, $_FILES['uploadFile']['name']);
    $data = mysqli_real_escape_string($connection, file_get_contents($_FILES ['uploadFile']['tmp_name']));

    $select_version = mysqli_query($connection, "SELECT version FROM filescontent ORDER BY fileID DESC LIMIT 1");
    $fetch_version = mysqli_fetch_assoc($select_version);
    $increment_version = $fetch_version['version'] + 1;
    echo '<br>'.$increment_version .' версия';

    $select_fileID = mysqli_query($connection, "SELECT fileID FROM filescontent ORDER BY fileID DESC LIMIT 1");
    $fetch_fileID = mysqli_fetch_assoc($select_fileID);
    $increment_fileID = $fetch_fileID["fileID"] + 1;
    echo '<br>'. $increment_fileID.'ID';

    $selectName = mysqli_query($connection, "SELECT fileName FROM files WHERE fileName='$name'");
    $fetchName = mysqli_fetch_assoc($selectName);
    $fetchName = $fetchName['fileName'];

    $selectIDname= "SELECT fileID FROM files WHERE fileName = '$name'";
    $selectIDnameQuery = mysqli_query($connection, $selectIDname);
    $row = mysqli_fetch_array($selectIDnameQuery);
    $selectIDname = $row['fileID'];
    echo '<br><pre>'.print_r($row, true).'</pre>';

    $a = mysqli_error($connection);
    echo '<br>'.$a.'<br>';  

    if(!strcmp($name, $fetchName)){
        echo 'The file exists';
        $query1 = mysqli_query($connection, "INSERT INTO filescontent (fileID, version, fileContent, author) VALUES ('$selectIDname', '$increment_version', '$data', 2)");
    }
    else{
        echo 'The file does not exist'; 
        $query2= mysqli_query($connection, "INSERT INTO filescontent (fileID, version, fileContent, author) VALUES ('$increment_fileID', 1, '$data', 2)");
        $query3 = mysqli_query($connection, "INSERT INTO files (fileID, fileName, ownerID) VALUES ('$increment_fileID', '$name', 2)");
    }

    $a = mysqli_error($connection);
    echo '<br>'.$a.'<br>';  
}

if（$\u POST）{
$name=mysqli\u real\u escape\u字符串（$connection，$\u FILES['uploadFile']['name']）；
$data=mysqli\u real\u escape\u string（$connection，file\u get\u contents（$\u FILES['uploadFile']['tmp\u name']）；
$select_version=mysqli_query（$connection，“按fileID DESC LIMIT 1从文件内容顺序选择版本”）；
$fetch\u version=mysqli\u fetch\u assoc（$select\u version）；
$increment_version=$fetch_version['version']+1；
回显“
”.$increment_version.“of theviewerббббб”；
if($_POST) {
    $name = mysqli_real_escape_string($connection, $_FILES['uploadFile']['name']);
$data = mysqli_real_escape_string($connection, file_get_contents($_FILES ['uploadFile']['tmp_name']));

$select_version = mysqli_query($connection, "SELECT version FROM filescontent ORDER BY fileID DESC LIMIT 1");
$fetch_version = mysqli_fetch_assoc($select_version);
$increment_version = (isset($fetch_version['version'])?$fetch_version['version']:0) + 1;
echo '<br>'.$increment_version .'<br>';

$select_fileID = mysqli_query($connection, "SELECT MAX(fileID) as fileID FROM filescontent ");
$fetch_fileID = mysqli_fetch_assoc($select_fileID);
$increment_fileID = (isset($fetch_fileID["fileID"])?$fetch_fileID["fileID"]:0) + 1;
echo '<br>'. $increment_fileID.'ID';

$selectIDname= "SELECT fileID FROM files WHERE fileName = '$name'";
$selectIDnameQuery = mysqli_query($connection, $selectIDname);
$row = mysqli_fetch_array($selectIDnameQuery);
$selectIDname = (isset($row['fileID']) ? $row['fileID']:null);
echo '<br><pre>'.print_r($row, true).'</pre>';

$a = mysqli_error($connection);
echo '<br>'.$a.'<br>';  

if(!empty($selectIDname)){
    echo 'The file exists';
    $query1 = mysqli_query($connection, "INSERT INTO filescontent (fileID, version, fileContent, author) VALUES ('$selectIDname', '$increment_version', '$data', 2)");
}
else{
    echo 'The file does not exist'; 
    $query2= mysqli_query($connection, "INSERT INTO filescontent (fileID, version, fileContent, author) VALUES ('$increment_fileID', 1, '$data', 2)");
    $query3 = mysqli_query($connection, "INSERT INTO files (fileID, fileName, ownerID) VALUES ('$increment_fileID', '$name', 2)");
}

$a = mysqli_error($connection);
echo '<br>'.$a.'<br>';  
}

$select_fileID=mysqli_query（$connection，“按fileID DESC LIMIT 1从filecontent顺序选择fileID”）；
$fetch\u fileID=mysqli\u fetch\u assoc（$select\u fileID）；
$increment_fileID=$fetch_fileID[“fileID”]+1；
回显“
”.$increment_fileID.ID”；
if($_POST) {
    $name = mysqli_real_escape_string($connection, $_FILES['uploadFile']['name']);
$data = mysqli_real_escape_string($connection, file_get_contents($_FILES ['uploadFile']['tmp_name']));

$select_version = mysqli_query($connection, "SELECT version FROM filescontent ORDER BY fileID DESC LIMIT 1");
$fetch_version = mysqli_fetch_assoc($select_version);
$increment_version = (isset($fetch_version['version'])?$fetch_version['version']:0) + 1;
echo '<br>'.$increment_version .'<br>';

$select_fileID = mysqli_query($connection, "SELECT MAX(fileID) as fileID FROM filescontent ");
$fetch_fileID = mysqli_fetch_assoc($select_fileID);
$increment_fileID = (isset($fetch_fileID["fileID"])?$fetch_fileID["fileID"]:0) + 1;
echo '<br>'. $increment_fileID.'ID';

$selectIDname= "SELECT fileID FROM files WHERE fileName = '$name'";
$selectIDnameQuery = mysqli_query($connection, $selectIDname);
$row = mysqli_fetch_array($selectIDnameQuery);
$selectIDname = (isset($row['fileID']) ? $row['fileID']:null);
echo '<br><pre>'.print_r($row, true).'</pre>';

$a = mysqli_error($connection);
echo '<br>'.$a.'<br>';  

if(!empty($selectIDname)){
    echo 'The file exists';
    $query1 = mysqli_query($connection, "INSERT INTO filescontent (fileID, version, fileContent, author) VALUES ('$selectIDname', '$increment_version', '$data', 2)");
}
else{
    echo 'The file does not exist'; 
    $query2= mysqli_query($connection, "INSERT INTO filescontent (fileID, version, fileContent, author) VALUES ('$increment_fileID', 1, '$data', 2)");
    $query3 = mysqli_query($connection, "INSERT INTO files (fileID, fileName, ownerID) VALUES ('$increment_fileID', '$name', 2)");
}

$a = mysqli_error($connection);
echo '<br>'.$a.'<br>';  
}

$selectName=mysqli_查询（$connection，“从文件名为“$name”的文件中选择文件名”）；
$fetchName=mysqli\u fetch\u assoc（$selectName）；
$fetchName=$fetchName['fileName']；
$selectIDname=“从文件名为“$name”的文件中选择文件ID”；
$selectIDnameQuery=mysqli\u查询（$connection，$selectIDname）；
$row=mysqli\u fetch\u数组（$selectIDnameQuery）；
$selectIDname=$row['fileID']；
回显“
”。打印（$row，true）。“”；
if($_POST) {
    $name = mysqli_real_escape_string($connection, $_FILES['uploadFile']['name']);
$data = mysqli_real_escape_string($connection, file_get_contents($_FILES ['uploadFile']['tmp_name']));

$select_version = mysqli_query($connection, "SELECT version FROM filescontent ORDER BY fileID DESC LIMIT 1");
$fetch_version = mysqli_fetch_assoc($select_version);
$increment_version = (isset($fetch_version['version'])?$fetch_version['version']:0) + 1;
echo '<br>'.$increment_version .'<br>';

$select_fileID = mysqli_query($connection, "SELECT MAX(fileID) as fileID FROM filescontent ");
$fetch_fileID = mysqli_fetch_assoc($select_fileID);
$increment_fileID = (isset($fetch_fileID["fileID"])?$fetch_fileID["fileID"]:0) + 1;
echo '<br>'. $increment_fileID.'ID';

$selectIDname= "SELECT fileID FROM files WHERE fileName = '$name'";
$selectIDnameQuery = mysqli_query($connection, $selectIDname);
$row = mysqli_fetch_array($selectIDnameQuery);
$selectIDname = (isset($row['fileID']) ? $row['fileID']:null);
echo '<br><pre>'.print_r($row, true).'</pre>';

$a = mysqli_error($connection);
echo '<br>'.$a.'<br>';  

if(!empty($selectIDname)){
    echo 'The file exists';
    $query1 = mysqli_query($connection, "INSERT INTO filescontent (fileID, version, fileContent, author) VALUES ('$selectIDname', '$increment_version', '$data', 2)");
}
else{
    echo 'The file does not exist'; 
    $query2= mysqli_query($connection, "INSERT INTO filescontent (fileID, version, fileContent, author) VALUES ('$increment_fileID', 1, '$data', 2)");
    $query3 = mysqli_query($connection, "INSERT INTO files (fileID, fileName, ownerID) VALUES ('$increment_fileID', '$name', 2)");
}

$a = mysqli_error($connection);
echo '<br>'.$a.'<br>';  
}

$a=mysqli\u错误（$connection）；
回音“
”.$a.
”；
if($_POST) {
    $name = mysqli_real_escape_string($connection, $_FILES['uploadFile']['name']);
$data = mysqli_real_escape_string($connection, file_get_contents($_FILES ['uploadFile']['tmp_name']));

$select_version = mysqli_query($connection, "SELECT version FROM filescontent ORDER BY fileID DESC LIMIT 1");
$fetch_version = mysqli_fetch_assoc($select_version);
$increment_version = (isset($fetch_version['version'])?$fetch_version['version']:0) + 1;
echo '<br>'.$increment_version .'<br>';

$select_fileID = mysqli_query($connection, "SELECT MAX(fileID) as fileID FROM filescontent ");
$fetch_fileID = mysqli_fetch_assoc($select_fileID);
$increment_fileID = (isset($fetch_fileID["fileID"])?$fetch_fileID["fileID"]:0) + 1;
echo '<br>'. $increment_fileID.'ID';

$selectIDname= "SELECT fileID FROM files WHERE fileName = '$name'";
$selectIDnameQuery = mysqli_query($connection, $selectIDname);
$row = mysqli_fetch_array($selectIDnameQuery);
$selectIDname = (isset($row['fileID']) ? $row['fileID']:null);
echo '<br><pre>'.print_r($row, true).'</pre>';

$a = mysqli_error($connection);
echo '<br>'.$a.'<br>';  

if(!empty($selectIDname)){
    echo 'The file exists';
    $query1 = mysqli_query($connection, "INSERT INTO filescontent (fileID, version, fileContent, author) VALUES ('$selectIDname', '$increment_version', '$data', 2)");
}
else{
    echo 'The file does not exist'; 
    $query2= mysqli_query($connection, "INSERT INTO filescontent (fileID, version, fileContent, author) VALUES ('$increment_fileID', 1, '$data', 2)");
    $query3 = mysqli_query($connection, "INSERT INTO files (fileID, fileName, ownerID) VALUES ('$increment_fileID', '$name', 2)");
}

$a = mysqli_error($connection);
echo '<br>'.$a.'<br>';  
}

如果（！strcmp（$name，$fetchName））{
回显“文件存在”；
$query1=mysqli_query（$connection，“插入到fileContent（fileID，version，fileContent，author）值（“$selectIDname”，“$increment_version”，“$data”，2）”）；
}
否则{
回显“文件不存在”；
$query2=mysqli_query（$connection，“插入到fileContent（fileID，version，fileContent，author）值（“$increment_fileID'，1，$data'，2）”）；
$query3=mysqli_query（$connection，“插入文件（fileID、fileName、ownerID）的值（“$increment_fileID”，“$name”，2）”）；
}
$a=mysqli\u错误（$connection）；
回音“
”.$a.
”；
if($_POST) {
    $name = mysqli_real_escape_string($connection, $_FILES['uploadFile']['name']);
$data = mysqli_real_escape_string($connection, file_get_contents($_FILES ['uploadFile']['tmp_name']));

$select_version = mysqli_query($connection, "SELECT version FROM filescontent ORDER BY fileID DESC LIMIT 1");
$fetch_version = mysqli_fetch_assoc($select_version);
$increment_version = (isset($fetch_version['version'])?$fetch_version['version']:0) + 1;
echo '<br>'.$increment_version .'<br>';

$select_fileID = mysqli_query($connection, "SELECT MAX(fileID) as fileID FROM filescontent ");
$fetch_fileID = mysqli_fetch_assoc($select_fileID);
$increment_fileID = (isset($fetch_fileID["fileID"])?$fetch_fileID["fileID"]:0) + 1;
echo '<br>'. $increment_fileID.'ID';

$selectIDname= "SELECT fileID FROM files WHERE fileName = '$name'";
$selectIDnameQuery = mysqli_query($connection, $selectIDname);
$row = mysqli_fetch_array($selectIDnameQuery);
$selectIDname = (isset($row['fileID']) ? $row['fileID']:null);
echo '<br><pre>'.print_r($row, true).'</pre>';

$a = mysqli_error($connection);
echo '<br>'.$a.'<br>';  

if(!empty($selectIDname)){
    echo 'The file exists';
    $query1 = mysqli_query($connection, "INSERT INTO filescontent (fileID, version, fileContent, author) VALUES ('$selectIDname', '$increment_version', '$data', 2)");
}
else{
    echo 'The file does not exist'; 
    $query2= mysqli_query($connection, "INSERT INTO filescontent (fileID, version, fileContent, author) VALUES ('$increment_fileID', 1, '$data', 2)");
    $query3 = mysqli_query($connection, "INSERT INTO files (fileID, fileName, ownerID) VALUES ('$increment_fileID', '$name', 2)");
}

$a = mysqli_error($connection);
echo '<br>'.$a.'<br>';  
}

}

使用下面提到的代码，我已经为您编写了它，并让我知道它是否适用于您：

if（$\u POST）{
$name=mysqli\u real\u escape\u字符串（$connection，$\u FILES['uploadFile']['name']）；
$data=mysqli\u real\u escape\u string（$connection，file\u get\u contents（$\u FILES['uploadFile']['tmp\u name']）；
$select_version=mysqli_query（$connection，“按fileID DESC LIMIT 1从文件内容顺序选择版本”）；
$fetch\u version=mysqli\u fetch\u assoc（$select\u version）；
$increment_version=（isset（$fetch_version['version']）？$fetch_version['version']：0）+1；
回显“
”.$increment_version.“
”；
if($_POST) {
    $name = mysqli_real_escape_string($connection, $_FILES['uploadFile']['name']);
$data = mysqli_real_escape_string($connection, file_get_contents($_FILES ['uploadFile']['tmp_name']));

$select_version = mysqli_query($connection, "SELECT version FROM filescontent ORDER BY fileID DESC LIMIT 1");
$fetch_version = mysqli_fetch_assoc($select_version);
$increment_version = (isset($fetch_version['version'])?$fetch_version['version']:0) + 1;
echo '<br>'.$increment_version .'<br>';

$select_fileID = mysqli_query($connection, "SELECT MAX(fileID) as fileID FROM filescontent ");
$fetch_fileID = mysqli_fetch_assoc($select_fileID);
$increment_fileID = (isset($fetch_fileID["fileID"])?$fetch_fileID["fileID"]:0) + 1;
echo '<br>'. $increment_fileID.'ID';

$selectIDname= "SELECT fileID FROM files WHERE fileName = '$name'";
$selectIDnameQuery = mysqli_query($connection, $selectIDname);
$row = mysqli_fetch_array($selectIDnameQuery);
$selectIDname = (isset($row['fileID']) ? $row['fileID']:null);
echo '<br><pre>'.print_r($row, true).'</pre>';

$a = mysqli_error($connection);
echo '<br>'.$a.'<br>';  

if(!empty($selectIDname)){
    echo 'The file exists';
    $query1 = mysqli_query($connection, "INSERT INTO filescontent (fileID, version, fileContent, author) VALUES ('$selectIDname', '$increment_version', '$data', 2)");
}
else{
    echo 'The file does not exist'; 
    $query2= mysqli_query($connection, "INSERT INTO filescontent (fileID, version, fileContent, author) VALUES ('$increment_fileID', 1, '$data', 2)");
    $query3 = mysqli_query($connection, "INSERT INTO files (fileID, fileName, ownerID) VALUES ('$increment_fileID', '$name', 2)");
}

$a = mysqli_error($connection);
echo '<br>'.$a.'<br>';  
}

$select_fileID=mysqli_query（$connection，“从filecontent中选择MAX（fileID）作为fileID”）；
$fetch\u fileID=mysqli\u fetch\u assoc（$select\u fileID）；
$increment_fileID=（isset（$fetch_fileID[“fileID”]）？$fetch_fileID[“fileID”]：0）+1；
回显“
”.$increment_fileID.ID”；
if($_POST) {
    $name = mysqli_real_escape_string($connection, $_FILES['uploadFile']['name']);
$data = mysqli_real_escape_string($connection, file_get_contents($_FILES ['uploadFile']['tmp_name']));

$select_version = mysqli_query($connection, "SELECT version FROM filescontent ORDER BY fileID DESC LIMIT 1");
$fetch_version = mysqli_fetch_assoc($select_version);
$increment_version = (isset($fetch_version['version'])?$fetch_version['version']:0) + 1;
echo '<br>'.$increment_version .'<br>';

$select_fileID = mysqli_query($connection, "SELECT MAX(fileID) as fileID FROM filescontent ");
$fetch_fileID = mysqli_fetch_assoc($select_fileID);
$increment_fileID = (isset($fetch_fileID["fileID"])?$fetch_fileID["fileID"]:0) + 1;
echo '<br>'. $increment_fileID.'ID';

$selectIDname= "SELECT fileID FROM files WHERE fileName = '$name'";
$selectIDnameQuery = mysqli_query($connection, $selectIDname);
$row = mysqli_fetch_array($selectIDnameQuery);
$selectIDname = (isset($row['fileID']) ? $row['fileID']:null);
echo '<br><pre>'.print_r($row, true).'</pre>';

$a = mysqli_error($connection);
echo '<br>'.$a.'<br>';  

if(!empty($selectIDname)){
    echo 'The file exists';
    $query1 = mysqli_query($connection, "INSERT INTO filescontent (fileID, version, fileContent, author) VALUES ('$selectIDname', '$increment_version', '$data', 2)");
}
else{
    echo 'The file does not exist'; 
    $query2= mysqli_query($connection, "INSERT INTO filescontent (fileID, version, fileContent, author) VALUES ('$increment_fileID', 1, '$data', 2)");
    $query3 = mysqli_query($connection, "INSERT INTO files (fileID, fileName, ownerID) VALUES ('$increment_fileID', '$name', 2)");
}

$a = mysqli_error($connection);
echo '<br>'.$a.'<br>';  
}

$selectIDname=“从文件名为“$name”的文件中选择文件ID”；
$selectIDnameQuery=mysqli\u查询（$connection，$selectIDname）；
$row=mysqli\u fetch\u数组（$selectIDnameQuery）；
$selectIDname=（isset（$row['fileID']）？$row['fileID']：null）；
回显“
”。打印（$row，true）。“”；
if($_POST) {
    $name = mysqli_real_escape_string($connection, $_FILES['uploadFile']['name']);
$data = mysqli_real_escape_string($connection, file_get_contents($_FILES ['uploadFile']['tmp_name']));

$select_version = mysqli_query($connection, "SELECT version FROM filescontent ORDER BY fileID DESC LIMIT 1");
$fetch_version = mysqli_fetch_assoc($select_version);
$increment_version = (isset($fetch_version['version'])?$fetch_version['version']:0) + 1;
echo '<br>'.$increment_version .'<br>';

$select_fileID = mysqli_query($connection, "SELECT MAX(fileID) as fileID FROM filescontent ");
$fetch_fileID = mysqli_fetch_assoc($select_fileID);
$increment_fileID = (isset($fetch_fileID["fileID"])?$fetch_fileID["fileID"]:0) + 1;
echo '<br>'. $increment_fileID.'ID';

$selectIDname= "SELECT fileID FROM files WHERE fileName = '$name'";
$selectIDnameQuery = mysqli_query($connection, $selectIDname);
$row = mysqli_fetch_array($selectIDnameQuery);
$selectIDname = (isset($row['fileID']) ? $row['fileID']:null);
echo '<br><pre>'.print_r($row, true).'</pre>';

$a = mysqli_error($connection);
echo '<br>'.$a.'<br>';  

if(!empty($selectIDname)){
    echo 'The file exists';
    $query1 = mysqli_query($connection, "INSERT INTO filescontent (fileID, version, fileContent, author) VALUES ('$selectIDname', '$increment_version', '$data', 2)");
}
else{
    echo 'The file does not exist'; 
    $query2= mysqli_query($connection, "INSERT INTO filescontent (fileID, version, fileContent, author) VALUES ('$increment_fileID', 1, '$data', 2)");
    $query3 = mysqli_query($connection, "INSERT INTO files (fileID, fileName, ownerID) VALUES ('$increment_fileID', '$name', 2)");
}

$a = mysqli_error($connection);
echo '<br>'.$a.'<br>';  
}

$a=mysqli\u错误（$connection）；
回音“
”.$a.
”；
if($_POST) {
    $name = mysqli_real_escape_string($connection, $_FILES['uploadFile']['name']);
$data = mysqli_real_escape_string($connection, file_get_contents($_FILES ['uploadFile']['tmp_name']));

$select_version = mysqli_query($connection, "SELECT version FROM filescontent ORDER BY fileID DESC LIMIT 1");
$fetch_version = mysqli_fetch_assoc($select_version);
$increment_version = (isset($fetch_version['version'])?$fetch_version['version']:0) + 1;
echo '<br>'.$increment_version .'<br>';

$select_fileID = mysqli_query($connection, "SELECT MAX(fileID) as fileID FROM filescontent ");
$fetch_fileID = mysqli_fetch_assoc($select_fileID);
$increment_fileID = (isset($fetch_fileID["fileID"])?$fetch_fileID["fileID"]:0) + 1;
echo '<br>'. $increment_fileID.'ID';

$selectIDname= "SELECT fileID FROM files WHERE fileName = '$name'";
$selectIDnameQuery = mysqli_query($connection, $selectIDname);
$row = mysqli_fetch_array($selectIDnameQuery);
$selectIDname = (isset($row['fileID']) ? $row['fileID']:null);
echo '<br><pre>'.print_r($row, true).'</pre>';

$a = mysqli_error($connection);
echo '<br>'.$a.'<br>';  

if(!empty($selectIDname)){
    echo 'The file exists';
    $query1 = mysqli_query($connection, "INSERT INTO filescontent (fileID, version, fileContent, author) VALUES ('$selectIDname', '$increment_version', '$data', 2)");
}
else{
    echo 'The file does not exist'; 
    $query2= mysqli_query($connection, "INSERT INTO filescontent (fileID, version, fileContent, author) VALUES ('$increment_fileID', 1, '$data', 2)");
    $query3 = mysqli_query($connection, "INSERT INTO files (fileID, fileName, ownerID) VALUES ('$increment_fileID', '$name', 2)");
}

$a = mysqli_error($connection);
echo '<br>'.$a.'<br>';  
}

如果（！empty（$selectIDname））{
回显“文件存在”；
$query1=mysqli_query（$connection，“插入到fileContent（fileID，version，fileContent，author）值（“$selectIDname”，“$increment_version”，“$data”，2）”）；
}
否则{
回显“文件不存在”；
$query2=mysqli_query（$connection，“插入到fileContent（fileID，version，fileContent，author）值（“$increment_fileID'，1，$data'，2）”）；
$query3=mysqli_query（$connection，“插入文件（fileID、fileName、ownerID）的值（“$increment_fileID”，“$name”，2）”）；
}
$a=mysqli\u错误（$connection）；
回音“
”.$a.
”；
if($_POST) {
    $name = mysqli_real_escape_string($connection, $_FILES['uploadFile']['name']);
$data = mysqli_real_escape_string($connection, file_get_contents($_FILES ['uploadFile']['tmp_name']));

$select_version = mysqli_query($connection, "SELECT version FROM filescontent ORDER BY fileID DESC LIMIT 1");
$fetch_version = mysqli_fetch_assoc($select_version);
$increment_version = (isset($fetch_version['version'])?$fetch_version['version']:0) + 1;
echo '<br>'.$increment_version .'<br>';

$select_fileID = mysqli_query($connection, "SELECT MAX(fileID) as fileID FROM filescontent ");
$fetch_fileID = mysqli_fetch_assoc($select_fileID);
$increment_fileID = (isset($fetch_fileID["fileID"])?$fetch_fileID["fileID"]:0) + 1;
echo '<br>'. $increment_fileID.'ID';

$selectIDname= "SELECT fileID FROM files WHERE fileName = '$name'";
$selectIDnameQuery = mysqli_query($connection, $selectIDname);
$row = mysqli_fetch_array($selectIDnameQuery);
$selectIDname = (isset($row['fileID']) ? $row['fileID']:null);
echo '<br><pre>'.print_r($row, true).'</pre>';

$a = mysqli_error($connection);
echo '<br>'.$a.'<br>';  

if(!empty($selectIDname)){
    echo 'The file exists';
    $query1 = mysqli_query($connection, "INSERT INTO filescontent (fileID, version, fileContent, author) VALUES ('$selectIDname', '$increment_version', '$data', 2)");
}
else{
    echo 'The file does not exist'; 
    $query2= mysqli_query($connection, "INSERT INTO filescontent (fileID, version, fileContent, author) VALUES ('$increment_fileID', 1, '$data', 2)");
    $query3 = mysqli_query($connection, "INSERT INTO files (fileID, fileName, ownerID) VALUES ('$increment_fileID', '$name', 2)");
}

$a = mysqli_error($connection);
echo '<br>'.$a.'<br>';  
}

}

你到底想做什么？现在没有发生什么？请查看

$mysqli->insert\u id

返回由上一个查询更新的自动增量字段的值。如果之前没有对连接进行查询，或者查询没有更新自动增量值，则返回零。

这里一切正常，但正如我所说，我必须获取用户上载的文件的ID。为什么要否定我的评分？在检查代码之前，您已给了我（-）ve。这不好，伙计，你应该先测试代码，我已经为你写了，当我添加一个文件时没关系，但是当我第二次添加它时，它不会进入数据库，当我第三次添加它时，它会进入数据库…：/留待，即使你不知道你的问题是什么。首先做好提问的准备，然后只给出答案