通过

IDataInitialize::LoadStringFromStorage

  • 项目

Loads a connection string.

Syntax

HRESULT LoadStringFromStorage(
   LPCOLESTR     pwszFileName,
   LPCOLESTR *   ppwszInitializationString);

Parameters

  • pwszFileName [in]
    Name of the file.

  • ppwszInitializationString [out]
    On exit, *ppwszInitializationString will contain the connection string.

Return Code

  • S_OK
    The method succeeded.

  • E_FAIL
    A provider-specific error occurred.

  • E_INVALIDARG
    pwszFileName was a null pointer.

    ppwszInitializationString was a null pointer.

  • STG_E_FILENOTFOUND
    The file indicated by pwszFileName was not found.

  • STG_E_ACCESSDENIED
    The caller has insufficient permission to open the file.

    The file is already open and locked for writing.

  • STG_E_INVALIDNAME
    pwszFileName was an invalid file name.

  • STG_E_INVALIDHEADER
    pwszFileName was a file that is not a UDL format file.

  • STG_E_PATHNOTFOUND
    The file was not found.

Comments

The ppwszInitializationString retrieved using this method will have any leading or trailing spaces trimmed from it. Hence, the string might not be exactly the same one as written using the IDataInitialize::WriteStringToStorage method. For example, passing in the string

   "Provider=MSDASQL.1; Integrated Security = 'SSPI'"

will be returned as

   "Provider=MSDASQL.1; Integrated Security = 'SSPI'"

When using .udl files to establish a connection, add "Udl Pooling" to the registry under the "SOFTWARE\Microsoft\DataAccess" key to improve performance. A Cache Size value greater than 0 (Cache Size=1) will enable the feature. A value of 100 is recommended.