I am editing the UpdateCommand of a typed dataset's tableadapter, and
noticing that the parameter dbtypes keep changing on me.  I've isolated the
problem down to these repeatable steps that occur even in Sql Server 2005
Express Edition:

1.  Create a new C# Windows Application
2.  Right-click the project and select "Add->New Item"
3.  Select "DataSet" and add it.  DataSet1.xsd should be in the project now
and should be open.
4.  In the VS Server Explorer, create a new Sql Server Express database
file.
5.  Create a new table in the newly-created database with the following
definition:
   CREATE TABLE FOO (Id bigint primary key, myfloat float)

6.  Expand the tables list for the new database you've made.
7.  Drag and drop the FOO table onto the typed dataset designer you added in
step 3.
8.  Right-click the typed dataset and select "Configure"
9.  Click the "Advanced Options" button, and turn off "Use optimistic
concurrency" and "Refresh the datatable".  Click OK afterwards.  This is
done strictly to simplify the steps that follow and reduce the number of
parameters in the update query.

10. Hit the "Finish" button.
11. Right-click the FOOTableAdapter and select "Properties"
12. Go to the UpdateCommand in the properties for FooTableAdapter and expand
it.
13. Examine the Parameters property, and ensure that the "myfloat" parameter
has a DbType of "Double".  Click OK or Cancel.
14. Press the "..." on the CommandText for the UpdateCommand to bring up the
Query Builder.
15. Do nothing in the Query Builder.  Press the OK button.
16. Examine the Parameters property for the UpdateCommand.  You will see
that the "myfloat" column now has a DbType of "Single".

This problem is much worse in my SQLite provider.  Int64's get changed to
Int32's, double's turn into decimal's, etc.  Re-configuring the typed
dataset (just right-click, hit Configure, and then Finish) will fix it back
to normal.  The Query Builder seems to be using some odd code path to
reconstruct these parameter types.

Robert Simpson
Programmer at Large