odbc

Haskell binding to the ODBC API, with a strong emphasis on stability, testing and simplicity.

Platform and database support

The following database drivers are tested against in CI:

• Microsoft SQL Server 2017

The following operating systems are tested against in CI:

• Windows
• Linux

I develop and test this library on OS X, but currently do not have a reliable way to run Microsoft SQL Server on Travis CI.

How ODBC works

ODBC is a C API that is split into a manager and a driver.

On Windows, there is an ODBC manager that comes with the OS. On Linux and OS X, the unixODBC package provides the same functionality.

Separately, for each database type, you have driver packages. When you provide a connection string, like this:

ODBC_TEST_CONNECTION_STRING='DRIVER={ODBC Driver 13 for SQL Server};SERVER=127.0.0.1;Uid=SA;Pwd=Passw0rd;Encrypt=no'

The DRIVER tells the ODBC API which library to use. In this case, it’s the recent SQL Server driver provided by Microsoft. Then, ODBC functions like SQLDriverConnectW will call that library.

How to connect to Microsoft SQL Server

In recent years, Microsoft has released binary drivers for SQL Server for Windows, Linux and OS X, with a guide for each operating system. That guide for the latest and greatest official Microsoft driver is here.

I have tested the OS X instructions on my own machine. This project’s Dockerfile follows setup instructions for Linux, and the AppVeyor file follows the setup instructions for Windows.

There is a test program that comes with the package called odbc which accepts a connection string as its argument. You can use this to test your connection easily.

(Use 17 instead of 13 if that’s the driver you installed.)

$ stack exec odbc 'DRIVER={ODBC Driver 13 for SQL Server};SERVER=192.168.99.101;Uid=SA;Pwd=Passw0rd;Encrypt=no'
> create table foo (i int)
Rows: 0
> insert into foo values (123123123)
Rows: 0
> select * from foo
123123123
Rows: 1

Common issues

Compilation on Linux/OS X may require a odbcss.h header file for type/constant definitions. To get this install the freetds package:

• Linux example.
• On OS X you can use brew install freetds.

Windows should already have this file.

If you see an error like this:

[unixODBC][Driver Manager]Can't open lib 'ODBC Driver 13 for SQL Server' : file not found

Then you might be trying to use the wrong driver. You might have installed version 17, so change the string to ODBC Driver 17 for SQL Server.

If you see an error like this:

[unixODBC][Driver Manager]Data source name not found and no default driver specified

This is a terrible error message. If passing your DSN via a shell environment variable or argument, check that your input string isn’t quoted e.g. "Driver=.." instead of Driver=.. due to silly shell scripting quoting issues.

If you see an error like this on OS X with driver version 17,

libc++abi.dylib: terminating with uncaught exception of type
std::runtime_error: collate_byname::collate_byname failed to construct
for C/en_AU.UTF-8/C/C/C/C

use driver 13 or see here for more detail.