在ODBC中为sqlconnectw函数指定DSN名称 [英] Specifying DSN names for the sqlconnectw function in ODBC

问题描述

以下是编译和工作：

rc = SQLConnect（ConHandle，（SQLWCHAR *）dailyworkbook，SQL_NTS，NULL，SQL_NTS，NULL，SQL_NTS）;



以下是编译，但我得到了运行时访问冲突：

c = SQLConnect（ConHandle，（SQLWCHAR *）Ldailyworkbook，SQL_NTS，NULL，SQL_NTS， NULL，SQL_NTS）;



我很困惑。任何见解都会有所帮助。



我尝试过：



在线帮助页面。 Visual Studio中的调试。

The following is compiling and working:
rc = SQLConnect(ConHandle, (SQLWCHAR*)"dailyworkbook", SQL_NTS, NULL, SQL_NTS, NULL, SQL_NTS);

The following is compiling but I get a run time access violation:
c = SQLConnect(ConHandle, (SQLWCHAR*)L"dailyworkbook", SQL_NTS, NULL, SQL_NTS, NULL, SQL_NTS);

I am puzzled. Any insight would be helpful.

What I have tried:

Online help pages. Debugging in Visual studio.

推荐答案

我不确定为什么会发生访问冲突，但可能是由于 UserName 和身份验证参数。当这些是 NULL 时，您还应传递零而不是 SQL_NTS 的长度：

I don't know for sure why the access violation occurs but it is probably due to the UserName and Authentication parameters. When those are NULL, you should also pass zero instead of SQL_NTS for the length:

c = SQLConnect(ConHandle, (SQLWCHAR*)L"dailyworkbook", SQL_NTS, NULL, 0, NULL, 0);

或通过空字符串，可以使用 SQL_NTS 或零

or pass empty strings which may use SQL_NTS or zero

c = SQLConnect(ConHandle, (SQLWCHAR*)L"dailyworkbook", SQL_NTS, (SQLWCHAR*)L"", SQL_NTS, (SQLWCHAR*)L"", SQL_NTS);

如果必须使用char或宽字符串取决于您的项目设置。以上假设您有一个Unicode项目。



我也只能猜到为什么你没有通过第一次调用获得访问冲突，但我认为这是一个潜力解释：

当使用Unicode构建并传递char字符串时，连接将失败，因为在使用其他参数之前无法找到服务器并且函数返回。

If you have to use char or wide strings depends on your project settings. The above assumes that you have a Unicode project.

I can also only guess why you did not get the access violation with the first call but I think this is a potential explanation:
When having a Unicode build and passing a char string, the connect will fail because the server can not be found and the function returns before using the additional parameters.

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