Re: ODBC C API question(s)

1. There is no direct equivalent for the mysql_fetch_lengths; But you 
could use SQLDescribeCol or SQLColAttribute(s) with SQL_ATTR_DESC_LENGTH 
to get column length. But you need to iterate through all fields like..

SQLExecDirect("select..");
SQLNumResultCols(&colCount);

for (i=1; i <= colCount; i++) {
    SQLColAttribute(colCount, SQL_ATTR_DESC_LENGTH)..
}

PS: its not a real example; but it is just a psedo code.

2. SQLDriverConnect has wrong usage; either you need to have valid 
window handle; else pass NULL for parameter 2.

3. UIDs/PWDs are optional. If you provide it overwrites the DSN UID/PWD. 
MySQL allows to store UID/PWD in DSN but few databases will not allow to 
store PWD due to security; For example; Oracle will not let you specify 
PWD in DSN.

4. For complete ODBC; check:

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/odbc/htm/dasdkodbcoverview.asp
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/odbc/htm/odbcabout_this_manual.asp


Patrick Galbraith wrote:
> Hi all,
> 
> I have been using the MySQL client API for quite some time now and am in 
> the middle of utilising ODBC C API for a current project. I'm wondering 
> if there is an equivalent call in ODBC for 'mysql_fetch_lengths' ?
> 
> Also, I am wondering what the difference is between
> 
> 
> SQLDriverConnect(dbc, (void *)1, "DSN=myodbc3patg", SQL_NTS,
>       outstr, sizeof(outstr), &outstrlen,
>             SQL_DRIVER_COMPLETE);
> 
> This fails, and I don't know why.
> 
> 
> But this works:
> 
> SQLConnect(V_OD_hdbc, (SQLCHAR*) "myodbc3patg", SQL_NTS,
>  (SQLCHAR*) "", SQL_NTS,
>  (SQLCHAR*) "", SQL_NTS);
> 
> What is the difference between the two? Is there any benefit/detriment 
> to either? The first snippet is from Easysoft's site, the second from 
> the tutorial on UNIX odbc.
> 
> I often see that people use a UID/Password with  ODBC  DSN. Why use a 
> password and also a DSN? I thought the DSN provides that? If one uses a 
> DSN with UID/Pass, does the UID/Password for the DSN get over-written?
> 
> Also, where are some good sites for the ODBC C API, with examples, 
> descriptions of the API calls? I have found info at Easysoft's website 
> as well as UnixODBC website. It seems that so much ODBC programming is 
> targeted for GUIs. Mine is all system-level that I want to accomplish.
> 
> Kind regards, thanks in advance!
> 
> Patrick
> 

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