A simple query should be a nobrainer right now. But what if
your programm runs on a system where you can't be sure which datasource names
are configured?
Then you should use SQLDataSources().
After allocating a environment handle you may use this to find out about the
DSN and the supplied description for the datasource.
As ODBC knows systemwide and userwide datasources, you need to give a direction
which datasource types you are looking for. There you may specify either of the
following values:
SQL_FETCH_FIRST |
Sets up SQLDataSources() to lookup the first of all
available datasources (either user or systemwide).
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SQL_FETCH_FIRST_USER |
Sets up SQLDataSources() to lookup the first of the
available user datasources.
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SQL_FETCH_FIRST_SYSTEM |
Sets up SQLDataSources() to lookup the first of the
available system datasources.
|
SQL_FETCH_NEXT |
Fetches the next datasource.
Depending on SQL_FETCH_FIRST_USER, SQL_FETCH_FIRST_SYSTEM
or SQL_FETCH_FIRST this may only be a user datasource,
only a system datasource or one of either.
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So let's have a look on a small function, which will return all available
datasource names. You may insert this code into the program which you built before and call it somewhere after you've obtained an environment handle.
void OD_ListDSN(void)
{
char l_dsn[100],l_desc[100];
short int l_len1,l_len2,l_next;
l_next=SQL_FETCH_FIRST;
while( SQLDataSources(V_OD_Env,l_next,l_dsn, sizeof(l_dsn),
&l_len1, l_desc, sizeof(l_desc), &l_len2) == SQL_SUCCESS)
{
printf("Server=(%s) Beschreibung=(%s)\n",l_dsn,l_desc);
l_next=SQL_FETCH_NEXT;
}
}
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