What are the ODBC connect details for the HR sample database?

Question

I have installed Oracle Express on Ubuntu 8.10 and read the Getting Started tutorials. Everything worked fine.
THE DSN
I need to connect via ODBC, to start with to the HR sample database on my PC.
The Getting Started tutorial says the userid and password are both hr, but what is the data source name (dsn) to be used with the SQLConnect?
THE INIs
The ini files below are the result of googling, not of any insight on my part.
/etc/odbcinst.ini
[OracleExpressdrv]
Driver = /usr/lib/oracle/xe/app/oracle/product/10.2.0/server/lib/libsqora.so.10.1
Description = Oracle 10g express driver
/etc/odbc.ini
[hrdsn]
Driver = OracleExpressdrv
Application Attributes = T
Attributes = W
BatchAutocommitMode = IfAllSuccessful
CloseCursor = F
DisableDPM = F
DisableMTS = T
DSN = TestDSN
EXECSchemaOpt =
EXECSyntax = T
Failover = T
FailoverDelay = 10
FailoverRetryCount = 10
FetchBufferSize = 64000
ForceWCHAR = F
Lobs = T
Longs = T
MetadataIdDefault = F
QueryTimeout = T
ResultSets = T
# ServerName is TNS_alias_from_tnsnames.ora
ServerName = OraDB
SQLGetData extensions = F
Translation DLL =
Translation Option = 0
UserID = ken
THE ENVIRONMENT
Before running my odbc test program I issued
LD_LIBRARY_PATH=/usr/lib/oracle/xe/app/oracle/product/10.2.0/server/lib;export LD_LIBRARY_PATH
and checked via env command that the ldlibpath actually had been set correctly.
After SQLConnect received the following error:
Usage error: SQLConnect: dsn=hrdsn, user=hr, password=hr <<< output by my test program
1: st=IM002, nerr=0, msg=
[unixODBC][Driver Manager]Data source name not found, and no default driver specified
The first part of the error message hints at there being something wrong with dsn=hrdsn. I don't understand the second part 'and no default driver specified'.
I am totally stuck. Advice would be most appreciated.

Answer 1

Oracle® Database Express Edition Installation Guide for Linux talks about Compiling the Oracle ODBC Driver Demos. It tells you to download and install the unixODBC DriverManager from unixODBC. On Ubuntu this is already preinstalled and/or available via the Synaptic Manager. It also instructs you to run a makefile demo_xe.mk to build an odbcdemo program. The makefile did not work for me (hundreds of compilation errors), but I looked at the odbcdemo.c code and could see that dsn=TESTDBDSN for user=hr and password=hr. In other words, by luck the demo program seems to be connecting to the HR sample database.
I changed the /etc/odbc.ini file to:
[TestDBDSN]
Application Attributes = T
Attributes = W
BatchAutocommitMode = IfAllSuccessful
CloseCursor = F
DisableDPM = F
DisableMTS = T
Driver = OracleExpressdrv
DSN = TestDBDSN
and also in my test program which now produced the following error:
Usage error: SQLConnect: dsn=TestDBDSN, user=hr, password=hr
1: st=IM004, nerr=0, msg=
[unixODBC][Driver Manager]Driver's SQLAllocHandle on SQL_HANDLE_HENV failed
which shows that the unixODBC driver manager has loaded the driver and that the driver immediately encountered problems.
The sql calls issued before the SQLConnect("TestDBDSN", "hr" , "hr") were OK, i.e. these:
rc0 = SQLAllocHandle ( SQL_HANDLE_ENV , SQL_NULL_HANDLE , &henv ) ;
rc = SQLSetEnvAttr ( henv, SQL_ATTR_ODBC_VERSION , *)SQL_OV_ODBC3 , 0 ) ;
rc = SQLAllocHandle ( SQL_HANDLE_DBC , henv , &hdbc ) ;
SQLSetConnectAttr ( hdbc , SQL_LOGIN_TIMEOUT , (void*)5 , 0 ) ;
However, the error appears after SQLConnect and yet the rc0 was reported as OK.
The error message 'Driver's SQLAllocHandle on SQL_HANDLE_HENV failed' is totally unhelpful to me as a user since I don't know the conditions that lead to failure. I really think this calls for some documentation. Such documentation should be complete, self-contained and correct and give ALL OPERATIONAL steps, i.e. I want to know exactly what I have to do. Ambiguous English often referring to undefined terms is not what Oracle beginners like myself want.
I don't know if this is a bug. It is so fundamental that Oracle ODBC driver writers could/should not have got it wrong. The connect does not even start.
I have googled for hours, but every lead has failed.
I don't want to give up on this. What can I do?