如何解压缩来自MS SQL VarBinary的数据并另存为文件？ （在PHP中）

Question

我正在尝试从php中的Microsoft SQL varbinary字段中检索文件。在插入数据库之前，这些文件在Visual Studio程序中使用IO.Compression.DeflateStream（）进行压缩。

我可以从数据库中获取文件，但我不确定如何解压缩文件：

 <?php
//assume that I already made the connection

$sql = "SELECT [FileData], [contentType] FROM dbo.Files where [FileGUID]='DAB88A50-E2C3-E311-A2D2-005056930304'";

$stmt= sqlsrv_query($conn , $sql);


if( $stmt === false ) {
    if( ($errors = sqlsrv_errors() ) != null) {
        foreach( $errors as $error ) {
            echo "SQLSTATE: ".$error[ 'SQLSTATE']."<br />";
            echo "code: ".$error[ 'code']."<br />";
            echo "message: ".$error[ 'message']."<br />";
        }
    }
}

$result = sqlsrv_fetch_array($stmt, SQLSRV_FETCH_ASSOC);
$filename = "test.pdf";
$X = $result['FileData'];

$contentType=  $result['ContentType'];
$filename=  $result['Filename'];


header("Content-Type:    $contentType; charset=utf-8");
header("Content-Disposition: attachment; filename=$filename");  //File name extension was wrong
header("Expires: 0");
header("Cache-Control: must-revalidate, post-check=0, pre-check=0");



//$X =  unpack('H*hex', $X);

echo $X;

?>

上面的PHP获取文件，但它仍然是压缩格式。

在VB中，我可以使用以下代码解压缩get文件：

 Dim Decompressed As Byte()
            Using ms As New IO.MemoryStream(b)

                Dim msOut As New IO.MemoryStream()

                Dim ds As New IO.Compression.DeflateStream(ms, IO.Compression.CompressionMode.Decompress)
                ds.CopyTo(msOut)

                Dim strPath As String = "d:\fsout\" + strDBName

                If (Not System.IO.Directory.Exists(strPath)) Then
                    System.IO.Directory.CreateDirectory(strPath)
                End If

                Dim file As New FileStream(strPath + "\" + strFilename, FileMode.Create, FileAccess.Write)
                msOut.WriteTo(file)
                file.Close()
                ms.Close()

                ds.Close()

我希望能用PHP做到这一点。有人知道在PHP中解压缩文件的技巧吗？我觉得这与php中的'unpack（）'有关，但不确定使用哪些参数。

Answer 1

回答我自己的问题

.NET使用zlib在IO.Compression.DeflateStream（）中进行压缩

所以我需要做的是：

$uncompressed = zlib_decode($X);
echo $uncompressed;

实际上在PHP中比VB更容易。

我的完整代码是：

 <?php
//assume that I already made the connection

$sql = "SELECT [FileData], [contentType] FROM dbo.Files where [FileGUID]='DAB88A50-E2C3-E311-A2D2-005056930304'";

$stmt= sqlsrv_query($conn , $sql);


if( $stmt === false ) {
    if( ($errors = sqlsrv_errors() ) != null) {
        foreach( $errors as $error ) {
            echo "SQLSTATE: ".$error[ 'SQLSTATE']."<br />";
            echo "code: ".$error[ 'code']."<br />";
            echo "message: ".$error[ 'message']."<br />";
        }
    }
}

$result = sqlsrv_fetch_array($stmt, SQLSRV_FETCH_ASSOC);
$filename = "test.pdf";
$X = $result['FileData'];

$contentType=  $result['ContentType'];
$filename=  $result['Filename'];


header("Content-Type:    $contentType; charset=utf-8");
header("Content-Disposition: attachment; filename=$filename");  //File name extension was wrong
header("Expires: 0");
header("Cache-Control: must-revalidate, post-check=0, pre-check=0");



//$X =  unpack('H*hex', $X);

echo $X;

?>