Add support for parameterised requests

[tediousjs]

Add support for parameterised requests

[baoshan]

Looking forward to that feature ^_^

[pekim]

Basic support for parameters has been added. Add parameters to the request, and call execSql as usual.

var TYPES = require('tedious').TYPES;

var request = new Request('select @param1, @anotherParam', function(err) {
    ....
});

request.addParameter(TYPES.VarChar, 'param1', 'qwerty');
request.addParameter(TYPES.Int, anotherParam', 42);

connection.execSql(request);

Output parameters can be added too. See issue #16 for an example.

Note: I am not convinced that the API is quite right. There's a good chance that it will change.

[zachaller]

same looking forward to this however on master or anything above this commit 5765a3d seems to break the request events 'row' and 'done'

[pekim]

The done event I might have an idea about, but a problem with row event would be puzzling. If it wasn't being emitted I'd expect a number of the integration tests to fail.

I'll take a look tomorrow, and try and recreate the problem.

[zachaller]

Ok also a bit more information, we are using it in a system of ours and the first statement that is running was an insert statement so that may be why the row event was not firing and so if that the expected behavior that is fine, the done event should still work though i would think.

[pekim]

Please note, the first two arguments to the Request.addParameter and Request.addOutputParameter functions have been swapped around. The first argument is now the parameter name.

request.addParameter('parameterName', TYPES.VarChar, string);
request.addParameter('anotherParameterName', TYPES.Int, number);

[pekim]

The parameterisation support was achieved using the sp_executesql procedure. This means that the doneProc event is emitted, when previously the done event would typically have been emitted. I suspect that trying to subvert TDS and hide this, would probably be difficult, and give rise to a never ending stream of edge case bugs.

Instead, I've added a row count parameter to the Request callback. So in many use cases the done, doneInProc and doneProc event can probably be ignored.

[pekim]

Included in v0.0.4.