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OpenSqlFilestream API

The OpenSqlFilestream API obtains a Win32 compatible file handle for a FILESTREAM binary large object (BLOB) that is stored in the file system.Herhangi aşağıdaki Win32 API'larının bir tanıtıcı geçirilebilir: ReadFile, WriteFile, TransmitFile, SetFilePointer, SetEndOfFile, veya FlushFileBuffers.Bu işleyici için diğer bir Win32 API aktarýrsanýz, ERROR_ACCESS_DENIED hata döndürülür.Win32 için ileterek Tanıtıcının kapatılması gerekir CloseHandle hareket tamamlandıktan veya geri önce API.İşleyicinin kapatılması başarısız olan sunucu tarafı kaynak sızıntılarını neden olur.

All FILESTREAM data container access must be performed in a SQL Server transaction.Transact-SQL statements can also be executed in the same transaction.Bu sql veri FILESTREAM blob verileri arasındaki tutarlılık korur.

FILESTREAM DAMLA, Win32 kullanarak erişmek için Windows Yetkilendirme etkinleştirilmiş olması gerekir.

Önemli notÖnemli

Dosya yazma erişimi için açıldığında, hareket FILESTREAM Aracısı tarafından aittir.Yalnızca Win32 dosya g/Ç işlemi serbest bırakılıncaya kadar izin verilir.Hareketin serbest bırakmak için yazma Tanıtıcının kapatılması gerekir.

Sözdizimi

HANDLE OpenSqlFilestream (
    LPCWSTR FilestreamPath,
    SQL_FILESTREAM_DESIRED_ACCESS DesiredAccess,
    ULONG OpenOptions,
    LPBYTE FilestreamTransactionContext,
    SIZE_T FilestreamTransactionContextLength,
    PLARGE_INTEGER AllocationSize);

Parametreler

  • FilestreamPath
    [in] İş nvarchar(max) tarafından döndürülen yol yol işlev.Sahip bir hesabı bağlamında yol adlı SQL Server seçin veya güncelleştirme izinleri FILESTREAM tablo ve sütun.

  • DesiredAccess
    [in] FILESTREAM blob veri erişim için kullanılan modu ayarlar.Bu değer için geçirilen DeviceIoControl işlevini.

    Ad

    Değer

    Anlamı

    SQL_FILESTREAM_READ

    0

    Veri dosyasından okunabilir.

    SQL_FILESTREAM_WRITE

    1

    Veri dosyaya yazılabilir.

    SQL_FILESTREAM_READWRITE

    2

    Veri Okuma ve dosyadan yazılmış.

    Not

    Bu değerler SQL_FILESTREAM_DESIRED_ACCESS numaralandırma sqlncli.h içinde tanımlanır.

  • OpenOptions
    [in] Dosya öznitelikleri ve işaretler.Bu parametreyi herhangi bir birleşimini aşağıdaki bayraklar da içerebilir.

    Bayrak

    Değer

    Anlamı

    SQL_FILESTREAM_OPEN_NONE

    0x00000000:

    Dosya kullanılıyor hiçbir özel seçenekler ile oluşturulan veya açılan.

    SQL_FILESTREAM_OPEN_FLAG_ASYNC

    0x00000001L

    Dosya kullanılıyor açıldığında veya zaman uyumsuz g/Ç için oluşturulmuş.

    SQL_FILESTREAM_OPEN_FLAG_NO_BUFFERING

    0x00000002L

    Sistem, sistem önbelleği kullanarak dosyayı açar.

    SQL_FILESTREAM_OPEN_FLAG_NO_WRITE_THROUGH

    0x00000004L

    Sistem, bir ara önbellek aracılığıyla yazmaz.Doğrudan diske yazma gidin.

    SQL_FILESTREAM_OPEN_FLAG_SEQUENTIAL_SCAN

    0x00000008L

    Bir dosyayı baştan sona sırayla erişilir.Sistem bu dosya önbelleğe almayı en iyi duruma getirmek için bir ipucu kullanabilirsiniz.Bir uygulama için rasgele erişimli Dosya işaretçisi taşırsa, en iyi önbelleğe alma gerçekleşmeyebilir.

    SQL_FILESTREAM_OPEN_FLAG_RANDOM_ACCESS

    0x00000010L

    Bir dosyayı rasgele erişilir.Sistem bu dosya önbelleğe almayı en iyi duruma getirmek için bir ipucu kullanabilirsiniz.

  • FilestreamTransactionContext
    [in] Tarafından döndürülen değeri GET_FILESTREAM_TRANSACTION_CONTEXT işlev.

  • FilestreamTransactionContextLength
    [in] Gelen bayt sayısı varbinary(max) tarafından döndürülen veriGET_FILESTREAM_TRANSACTION_CONTEXT işlev. işlev n bayt dizisi döndürür.N işlev tarafından belirlenir ve döndürülen bayt dizisi özellik.

  • AllocationSize
    [in] Veri dosyasının ilk ayırma boyutunu bayt cinsinden belirtir.Okuma modunda göz ardı edilir.Bu parametre null, dosya sistem davranışı durum kullanılan olabilir.

Dönüş Değeri

işlev başarılı olursa, dönüş açık belirtilen dosya tanıtıcısı değerdir.işlev başarısız olursa, dönüş INVALID_HANDLE_VALUE değerdir.Genişletilmiş hata bilgileri için çağrı GetLastError().

Örnekler

Aşağıdaki örnekler, nasıl kullanacağınızı gösteren OpenSqlFilestream API elde bir Win32 işleyicisi.

using System.IO;
using System;
using System.Collections.Generic;
using System.Text;
using System.Data;
using System.Data.SqlClient;
using System.Data.SqlTypes;

namespace FILESTREAM
{
    class Program
    {
        static void Main(string[] args)
        {
            SqlConnection sqlConnection = new SqlConnection(
                "Integrated Security=true;server=(local)");

            SqlCommand sqlCommand = new SqlCommand();
            sqlCommand.Connection = sqlConnection;

            try
            {
                sqlConnection.Open();

                //The first task is to retrieve the file path
                //of the SQL FILESTREAM BLOB that we want to
                //access in the application.

                sqlCommand.CommandText =
                      "SELECT Chart.PathName()"
                    + " FROM Archive.dbo.Records"
                    + " WHERE SerialNumber = 3";

                String filePath = null;

                Object pathObj = sqlCommand.ExecuteScalar();
                if (DBNull.Value != pathObj)
                    filePath = (string)pathObj;
                else
                {
                    throw new System.Exception(
                        "Chart.PathName() failed"
                      + " to read the path name "
                      + " for the Chart column.");
                }

                //The next task is to obtain a transaction
                //context. All FILESTREAM BLOB operations
                //occur within a transaction context to
                //maintain data consistency.

                //All SQL FILESTREAM BLOB access must occur in 
                //a transaction. MARS-enabled connections
                //have specific rules for batch scoped transactions,
                //which the Transact-SQL BEGIN TRANSACTION statement
                //violates. To avoid this issue, client applications 
                //should use appropriate API facilities for transaction management, 
                //management, such as the SqlTransaction class.

                SqlTransaction transaction = sqlConnection.BeginTransaction("mainTranaction");
                sqlCommand.Transaction = transaction;

                sqlCommand.CommandText =
                    "SELECT GET_FILESTREAM_TRANSACTION_CONTEXT()";

                Object obj = sqlCommand.ExecuteScalar();
                byte[] txContext = (byte[])obj;

                //The next step is to obtain a handle that
                //can be passed to the Win32 FILE APIs.

                SqlFileStream sqlFileStream = new SqlFileStream(filePath, txContext, FileAccess.ReadWrite);

                byte[] buffer = new byte[512];

                int numBytes = 0;

                //Write the string, "EKG data." to the FILESTREAM BLOB.
                //In your application this string would be replaced with
                //the binary data that you want to write.

                string someData = "EKG data.";
                Encoding unicode = Encoding.GetEncoding(0);

                sqlFileStream.Write(unicode.GetBytes(someData.ToCharArray()),
                    0,
                    someData.Length);

                //Read the data from the FILESTREAM
                //BLOB.

                sqlFileStream.Seek(0L, SeekOrigin.Begin);

                numBytes = sqlFileStream.Read(buffer, 0, buffer.Length);

                string readData = unicode.GetString(buffer);

                if (numBytes != 0)
                    Console.WriteLine(readData);

                //Because reading and writing are finished, FILESTREAM 
                //must be closed. This closes the c# FileStream class, 
                //but does not necessarily close the the underlying 
                //FILESTREAM handle. 
                sqlFileStream.Close();

                //The final step is to commit or roll back the read and write
                //operations that were performed on the FILESTREAM BLOB.

                sqlCommand.Transaction.Commit();
            }
            catch (System.Exception ex)
            {
                Console.WriteLine(ex.ToString());
            }
            finally
            {
                sqlConnection.Close();
            }
            return;
        }
    }
}
Imports System.IO
Imports System 
Imports System.Collections.Generic 
Imports System.Text 
Imports System.Data 
Imports System.Data.SqlClient 
Imports System.Data.SqlTypes 

Module Module1
    Public Sub Main(ByVal args As String())
        '        Dim sqlConnection As New SqlConnection("Integrated Security=true;server=(local)")
        Dim sqlConnection As New SqlConnection("Integrated Security=true;server=kellyreyue\MSSQL1")

        Dim sqlCommand As New SqlCommand()
        sqlCommand.Connection = sqlConnection

        Try
            sqlConnection.Open()

            'The first task is to retrieve the file path 
            'of the SQL FILESTREAM BLOB that we want to 
            'access in the application. 

            sqlCommand.CommandText = "SELECT Chart.PathName()" + " FROM Archive.dbo.Records" + " WHERE SerialNumber = 3"

            Dim filePath As String = Nothing

            Dim pathObj As Object = sqlCommand.ExecuteScalar()
            If Not pathObj.Equals(DBNull.Value) Then
                filePath = DirectCast(pathObj, String)
            Else
                Throw New System.Exception("Chart.PathName() failed" + " to read the path name " + " for the Chart column.")
            End If

            'The next task is to obtain a transaction 
            'context. All FILESTREAM BLOB operations 
            'occur within a transaction context to 
            'maintain data consistency. 

            'All SQL FILESTREAM BLOB access must occur in 
            'a transaction. MARS-enabled connections 
            'have specific rules for batch scoped transactions, 
            'which the Transact-SQL BEGIN TRANSACTION statement 
            'violates. To avoid this issue, client applications 
            'should use appropriate API facilities for transaction management, 
            'management, such as the SqlTransaction class. 

            Dim transaction As SqlTransaction = sqlConnection.BeginTransaction("mainTranaction")
            sqlCommand.Transaction = transaction

            sqlCommand.CommandText = "SELECT GET_FILESTREAM_TRANSACTION_CONTEXT()"

            Dim obj As Object = sqlCommand.ExecuteScalar()
            Dim txContext As Byte() = Nothing

            Dim contextLength As UInteger

            If Not obj.Equals(DBNull.Value) Then
                txContext = DirectCast(obj, Byte())
                contextLength = txContext.Length()
            Else
                Dim message As String = "GET_FILESTREAM_TRANSACTION_CONTEXT() failed"
                Throw New System.Exception(message)
            End If

            'The next step is to obtain a handle that 
            'can be passed to the Win32 FILE APIs. 

            Dim sqlFileStream As New SqlFileStream(filePath, txContext, FileAccess.ReadWrite)

            Dim buffer As Byte() = New Byte(511) {}

            Dim numBytes As Integer = 0

            'Write the string, "EKG data." to the FILESTREAM BLOB. 
            'In your application this string would be replaced with 
            'the binary data that you want to write. 

            Dim someData As String = "EKG data."
            Dim unicode As Encoding = Encoding.GetEncoding(0)

            sqlFileStream.Write(unicode.GetBytes(someData.ToCharArray()), 0, someData.Length)

            'Read the data from the FILESTREAM 
            'BLOB. 

            sqlFileStream.Seek(0, SeekOrigin.Begin)

            numBytes = sqlFileStream.Read(buffer, 0, buffer.Length)

            Dim readData As String = unicode.GetString(buffer)

            If numBytes <> 0 Then
                Console.WriteLine(readData)
            End If

            'Because reading and writing are finished, FILESTREAM 
            'must be closed. This closes the c# FileStream class, 
            'but does not necessarily close the the underlying 
            'FILESTREAM handle. 
            sqlFileStream.Close()

            'The final step is to commit or roll back the read and write 
            'operations that were performed on the FILESTREAM BLOB. 

            sqlCommand.Transaction.Commit()
        Catch ex As System.Exception
            Console.WriteLine(ex.ToString())
        Finally
            sqlConnection.Close()
        End Try
        Return
    End Sub
End Module
#include <windows.h>
#include <sql.h>
#include<sqltypes.h>
#include<sqlext.h>
#include <stdio.h>
#include <sqlncli.h>

#define COPYBUFFERSIZE 4096

/// <summary>
///This class iterates though the ODBC error queue and prints all of the
///accumulated error messages to the console.
/// </summary>

class ODBCErrors
{
private:
    int         m_iLine;    //Source code line on which the error occurred
    SQLSMALLINT m_type;     //Type of handle on which the error occurred
    SQLHANDLE   m_handle;   //ODBC handle on which the error occurred

public:
    /// <summary>
    ///Default constructor for the ODBCErrors class
    ///</summary>

    ODBCErrors()
    {
        m_iLine  = -1;
        m_type   = 0;
        m_handle = SQL_NULL_HANDLE;
    }

    /// <summary>
    ///Constructor for the ODBCErrors class
    /// </summary>
    /// <param name="iLine">
    /// This parameter is the source code line
    /// at which the error occurred.
    ///</param>
    /// <param name="type">
    /// This parameter is the type of ODBC handle passed in
    /// the next parameter.
    ///</param>
    /// <param name="handle">
    /// This parameter is the handle on which the error occurred.
    ///</param>

    ODBCErrors(int iLine, SQLSMALLINT type, SQLHANDLE handle)
    {
        m_iLine  = iLine;
        m_type   = type;
        m_handle = handle;
    }

    ///<summary>
    /// This method iterates though the error stack for the handle passed
    /// into the constructor and displays those errors on the console.
    ///</summary>

    void Print()
    {
        SQLSMALLINT i = 0, len = 0;
        SQLINTEGER  native;
        SQLTCHAR    state[9], text[256];
        SQLRETURN   sqlReturn = SQL_SUCCESS;

        if ( m_handle == SQL_NULL_HANDLE )
        {
            wprintf_s(TEXT("The error handle is not a valid handle.\n"), m_iLine);
            return;
        }

        wprintf_s(TEXT("Error Line(%d)\n"), m_iLine);

        while( sqlReturn == SQL_SUCCESS )
        {
            len = 0;

            sqlReturn = SQLGetDiagRec(
                m_type,
                m_handle,
                ++i,
                state,
                &native,
                text,
                sizeof(text)/sizeof(SQLTCHAR),
                &len);

            if ( SQL_SUCCEEDED(sqlReturn) )
                wprintf_s(TEXT("Error(%d, %ld, %s) : %s\n"), i, native, state, text);
        }
    }
};


BOOL CopyFileToSQL(LPTSTR srcFilePath, LPTSTR dstFilePath, LPBYTE transactionToken, SQLINTEGER cbTransactionToken)
{
    BOOL bRetCode = FALSE;

    HANDLE srcHandle = INVALID_HANDLE_VALUE;
    HANDLE dstHandle = INVALID_HANDLE_VALUE;
    BYTE   buffer[COPYBUFFERSIZE] = { 0 };

    TCHAR *szErrMsgSrc   = TEXT("Error opening source file.");
    TCHAR *szErrMsgDst   = TEXT("Error opening destFile file.");
    TCHAR *szErrMsgRead  = TEXT("Error reading source file.");
    TCHAR *szErrMsgWrite = TEXT("Error writing SQL file.");

    try
    {
        if ( (srcHandle = CreateFile(
            srcFilePath,
            GENERIC_READ,
            FILE_SHARE_READ,
            NULL,
            OPEN_EXISTING,
            FILE_FLAG_SEQUENTIAL_SCAN,
            NULL)) == INVALID_HANDLE_VALUE )
            throw szErrMsgSrc;

        if ( (dstHandle =  OpenSqlFilestream(
            dstFilePath,
            Write,
            0,
            transactionToken,
            cbTransactionToken,
            0)) == INVALID_HANDLE_VALUE)
            throw szErrMsgDst;

        DWORD bytesRead = 0;
        DWORD bytesWritten = 0;

        do
        {
            if ( ReadFile(srcHandle, buffer, COPYBUFFERSIZE, &bytesRead, NULL) == 0 )
                throw szErrMsgRead;

            if (bytesRead > 0)
            {
                if ( WriteFile(dstHandle, buffer, bytesRead, &bytesWritten, NULL) == 0 )
                    throw szErrMsgWrite;
            }
        } while (bytesRead > 0);

        bRetCode = TRUE;
    }
    catch( TCHAR *szErrMsg )
    {
        wprintf_s(szErrMsg);
        bRetCode = FALSE;
    }

    if ( srcHandle != INVALID_HANDLE_VALUE )
        CloseHandle(srcHandle);

    if ( dstHandle != INVALID_HANDLE_VALUE )
        CloseHandle(dstHandle);

    return bRetCode;
}

void main()
{
    TCHAR *sqlDBQuery =
       TEXT("INSERT INTO Archive.dbo.Records(Id, SerialNumber, Chart)")
       TEXT(" OUTPUT GET_FILESTREAM_TRANSACTION_CONTEXT(), inserted.Chart.PathName()")
       TEXT("VALUES (newid (), 5, CONVERT(VARBINARY, '**Temp**'))");

    SQLCHAR transactionToken[32];

    SQLHANDLE henv = SQL_NULL_HANDLE;
    SQLHANDLE hdbc              = SQL_NULL_HANDLE;
    SQLHANDLE hstmt             = SQL_NULL_HANDLE;

    try
    {
        //These statements Initialize ODBC for the client application and
        //connect to the database.

        if ( SQLAllocHandle(SQL_HANDLE_ENV, SQL_NULL_HANDLE, &henv) != SQL_SUCCESS )
            throw new ODBCErrors(__LINE__, SQL_HANDLE_ENV, henv);

        if ( SQLSetEnvAttr(henv, SQL_ATTR_ODBC_VERSION,(void*)SQL_OV_ODBC3, NULL) != SQL_SUCCESS )
            throw new ODBCErrors(__LINE__, SQL_HANDLE_ENV, henv);

        if ( SQLAllocHandle(SQL_HANDLE_DBC, henv, &hdbc) != SQL_SUCCESS )
            throw new ODBCErrors(__LINE__, SQL_HANDLE_ENV, henv);

        //This code assumes that the dataset name "Sql Server FILESTREAM"
        //has been previously created on the client computer system. An
        //ODBC DSN is created with the ODBC Data Source item in
        //the Windows Control Panel.

        if ( SQLConnect(hdbc, TEXT("Sql Server FILESTREAM"),
                SQL_NTS, NULL, 0, NULL, 0) <= 0 )
            throw new ODBCErrors(__LINE__, SQL_HANDLE_DBC, hdbc);

        //FILESTREAM requires that all read and write operations occur
        //within a transaction.
        if ( SQLSetConnectAttr(hdbc,
            SQL_ATTR_AUTOCOMMIT,
            (SQLPOINTER)SQL_AUTOCOMMIT_OFF,
            SQL_IS_UINTEGER) != SQL_SUCCESS )
            throw new ODBCErrors(__LINE__, SQL_HANDLE_DBC, hdbc);

        if ( SQLAllocHandle(SQL_HANDLE_STMT, hdbc, &hstmt) != SQL_SUCCESS )
            throw new ODBCErrors(__LINE__, SQL_HANDLE_DBC, hdbc);

        if ( SQLExecDirect(hstmt, sqlDBQuery, SQL_NTS) != SQL_SUCCESS )
            throw new ODBCErrors(__LINE__, SQL_HANDLE_STMT, hstmt);

        //Retrieve the transaction token.
        if ( SQLFetch(hstmt) != SQL_SUCCESS )
            throw new ODBCErrors(__LINE__, SQL_HANDLE_STMT, hstmt);

        SQLINTEGER cbTransactionToken = sizeof(transactionToken);

        if ( SQLGetData(hstmt, 1,
            SQL_C_BINARY,
            transactionToken,
            sizeof(transactionToken),
            &cbTransactionToken) != SQL_SUCCESS )
            throw new ODBCErrors(__LINE__, SQL_HANDLE_STMT, hstmt);

        //Retrieve the file path for the inserted record.

        TCHAR dstFilePath[1024];
        SQLINTEGER cbDstFilePath;

        if ( SQLGetData(hstmt, 2, SQL_C_TCHAR, dstFilePath, sizeof(dstFilePath), &cbDstFilePath) != SQL_SUCCESS )
            throw new ODBCErrors(__LINE__, SQL_HANDLE_STMT, hstmt);

        if ( SQLCloseCursor(hstmt) != SQL_SUCCESS )
            throw new ODBCErrors(__LINE__, SQL_HANDLE_STMT, hstmt);

        SQLUSMALLINT mode = SQL_ROLLBACK;

        if ( CopyFileToSQL(
            TEXT("C:\\Users\\Data\\chart1.jpg"),
            dstFilePath,
            transactionToken,
            cbTransactionToken) == TRUE )
            mode = SQL_COMMIT;

        SQLTransact(henv, hdbc, mode);
    }
    catch(ODBCErrors *pErrors)
    {
        pErrors->Print();
        delete pErrors;
    }

    if ( hstmt != SQL_NULL_HANDLE )
        SQLFreeHandle(SQL_HANDLE_STMT, hstmt);

    if ( hdbc != SQL_NULL_HANDLE )
        SQLDisconnect(hdbc);

    if ( hdbc != SQL_NULL_HANDLE )
        SQLFreeHandle(SQL_HANDLE_DBC, hdbc); 

    if ( henv != SQL_NULL_HANDLE )
        SQLFreeHandle(SQL_HANDLE_ENV, henv);
}

Açıklamalar

The SQL Server Native Client must be installed to use this API.The SQL Server Native Client is installed with SQL Server or SQL Server client tools.Daha fazla bilgi için bkz: SQL Server Native Client Yükleme.