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SQLReadFileDSN Function

  • Artikkeli

Conformance
Version Introduced: ODBC 3.0

Summary
SQLReadFileDSN reads information from a File DSN.

Syntax

  
BOOL SQLReadFileDSN(  
     LPCSTR   lpszFileName,  
     LPCSTR   lpszAppName,  
     LPCSTR   lpszKeyName,  
     LPSTR    lpszString,  
     WORD     cbString,  
     WORD *   pcbString);

Arguments

lpszFileName
[Input] Pointer to the data buffer containing the name of the .dsn file. A .dsn extension is appended to all file names that do not already have a .dsn extension. The value in *lpszFileName must be a null-terminated string.

lpszAppName
[Input] Pointer to the data buffer containing the name of the application. This is "ODBC" for the ODBC section. The value in *lpszAppName must be a null-terminated string.

lpszKeyName
[Input] Pointer to the data buffer containing the name of the key to be read. See "Comments" for reserved keywords. The value in *lpszAppName must be a null-terminated string.

lpszString
[Output] Pointer to the data buffer containing the string associated with the key to be read.

If *lpszFileName is a valid .dsn file name but the lpszAppName argument is a null pointer and the lpszKeyName argument is a null pointer, then *lpszString contains a list of valid applications. If *lpszFileName is a valid .dsn file name and *lpszAppName is a valid application name, but the lpszKeyName argument is a null pointer, then *lpszString contains a list of valid reserved keywords in the appropriate section of the DSN file, delimited by semicolons. If *lpszFileName is a valid .dsn file name but *lpszAppName is a null pointer and the lpszKeyName argument is a null pointer, then *lpszString contains a list of the sections in the DSN file, delimited by semicolons.

cbString
[Input] Length of the *lpszString buffer.

pcbString
[Output] Total number of bytes available to return in *lpszString. If the number of bytes available to return is greater than or equal to cbString, the output string in *lpszString is truncated to cbString minus the null-termination character. The pcbString argument can be a null pointer.

Returns

The function returns TRUE if it is successful, FALSE if it fails.

Diagnostics

When SQLReadFileDSN returns FALSE, an associated *pfErrorCode value can be obtained by calling SQLInstallerError. The following table lists the *pfErrorCode values that can be returned by SQLInstallerError and explains each one in the context of this function.

*pfErrorCode Error Description
ODBC_ERROR_GENERAL_ERR General installer error An error occurred for which there was no specific installer error.
ODBC_ERROR_INVALID_BUFF_LEN Invalid buffer length The lpszString argument was NULL.

The cbString argument was less than or equal to 0.
ODBC_ERROR_INVALID_PATH Invalid install path The path of the file name specified in the lpszFileName argument was invalid.
ODBC_ERROR_INVALID_REQUEST_TYPE Invalid type of request The lpszAppName argument was NULL, while the lpszKeyName argument was valid.
ODBC_ERROR_OUT_OF_MEM Out of memory The installer could not perform the function because of a lack of memory.
ODBC_ERROR_OUTPUT_STRING_TRUNCATED Output string truncated The string returned in *lpszString was truncated because the value in cbString was less than or equal to the value in *pcbString.
ODBC_ERROR_REQUEST_FAILED Request failed The keyword did not exist in the file DSN.

Comments

ODBC reserves the section name [ODBC] in which to store the connection information. The reserved keywords for this section are the same as those reserved for a connect string in SQLDriverConnect. (For more information, see the SQLDriverConnect function description.)

Applications can use these reserved keywords to read the information in a File DSN. If an applications wants to find out the DSN-less connection string associated with a File DSN, it can call SQLReadFileDSN for any of the reserved connection string keywords in the [ODBC] section. The full connection string passed in a DSN-less connection is a combination of all of the keywords (reserved and driver-specific) in the [ODBC] section.

For information about See
Writing information to a File DSN SQLWriteFileDSN