add parameterised value support for text

[zachaller]

This allows support for text types to be parameters however TDS dose not allow text to be ouput parameters so that is not supported as well as I had some issue with empty string such as '' from my understanding it my not be supported (http://lists.ibiblio.org/pipermail/freetds/2010q2/025787.html) and if so the test case for it should either be removed or modified.

Signed-off-by: Zach Aller zachaller@hotmail.com

[pekim]

Thanks for this. It's great to see the integration tests.

Regarding the null vs. empty string issue, I think that you may have uncovered a bug in the parsing of text values in tedious. A test added to datatypes-in-results-test.coffee fails with AssertionError: "" === null.

  exports.textEmpty = (test) ->
    execSql(test, "select cast('' as text) as text", '')

I can see that the response from the server is different from the one from this, passing, test.

  exports.textNull = (test) ->
    execSql(test, "select cast(null as text) as text", null)

So I think that it may be fixable. I'm digging in to the details of the response now.

[pekim]

Empty (zero-length) values for test/ntext/image columns were not being distinguished from null values.
I've fixed this in fd7ead7.

The failing test for an empty text parameter now passes.

Thanks again for this PR.