Oracle – Microsoft – ODBC Driver Manager – Data source name not found and no default driver specified

instantclientodbcoraclewinapi

I have developed an app in VC++ to make connect to Oracle DB and access its data. It requires a DSN to be created and some environment variables like PATH, ORACLE_HOME, TNS_ADMIN, etc. to be set which I have done programmatically in my VC++ code. I have updated required registry entries. I have installed 32bit Oracle Instant Client on my machine.

http://download.oracle.com/otn/nt/instantclient/121020/instantclient-basic-nt-12.1.0.2.0.zip
http://download.oracle.com/otn/nt/instantclient/121020/instantclient-odbc-nt-12.1.0.2.0.zip

I have complied and built the application exe using Win32 option as target platform on Windows 7 64 bit machine. This exe works fine on Windows 7 64 bit machine and I am able to make the DB connection successfully using SQLDriverConnect().

But when I do same setup on Windows 32 bit machine like installing 32bit Oracle Instant Client, setting some environment variables like PATH, ORACLE_HOME, TNS_ADMIN, etc., updating required registry entries and try running same application exe (used on 64 bit machine), this gives following error:

[Microsoft] – [ODBC Driver Manager] Data source name not found and no default driver specified.

Please suggest the resolution steps.

Best Answer

Where did you define your ODBC data sources? You have to do this separately

for 64-bit use %SYSTEMROOT%\system32\odbcad32.exe (typically c:\windows\system32\odbcad32.exe)

and for 32-bit use %SYSTEMROOT%\SysWOW64\odbcad32.exe (typically c:\Windows\SysWOW64\odbcad32.exe)

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