[chocus aterguss]

:plain:Hi there;

I'm racking my brains for a while and haven't found the solution for this:

[list=1]
[list]

[*]I'm using VS 2005 and a Type Dataset( WINFORM)
[*]I add two tables (Parent and child) with the proper relation
[*]I add a calculated column in the Parent table with the following expression (Parent.[columnname]).
[*]At run time the calculated column returns a null vale.

I don't really know what's wrong generating calculated columns with Type dataset.
No run-time error just only null vales ...please help.

[baavgai]

Take the "Parent." out. There is no table scope in the declaration. You can't look at other tables.

You can do this:

DataSet ds = new DataSet();
DataTable dt = ds.Tables.Add("Test");
dt.Columns.Add("ColAlpha", typeof(int));
DataColumn dc = dt.Columns.Add("ColBeta", typeof(int));
dc.Expression = "[ColAlpha]";

Not:

dc.Expression = "Test.[ColAlpha]";

More here: http://msdn.microsof...n(v=VS.71).aspx

[JackOfAllTrades]

Moved to C#

[chocus aterguss]

Hi There:
I'm using VS 2205 in winForms (C#).I created a strong Type Dataset using the UIE wizard of VS2005. I added a couple of datatables parent-child with their relationship. I put a calculated column in the child table using Expresion= Parent.columnname.
On runtime the dataset return a null calculated column.
In another hand, I have tried another way around by I coding the dataset (untype) and the calculated column works smoothly.

Is it a bug of this version or I'm missing something?
PLEASE HELP !!!!!!

[JackOfAllTrades]

The answer in your previous topic was insufficient?

[PsychoCoder]

Topics merged, there's no need for duplicate topics.

[baavgai]

Check your relation. Also, the docs are unclear how to handle multiple parents.

Assuming the relation is set correctly, Parent should work.

e.g.

DataSet ds = new DataSet();
DataTable dt1 = ds.Tables.Add("Deparment");
dt1.Columns.Add("DeptId", typeof(int));
dt1.Columns.Add("Description", typeof(string));
dt1.Constraints.Add("PkDepartment", dt1.Columns["DeptId"], true);

DataTable dt2 = ds.Tables.Add("Employee");
dt2.Columns.Add("EmpId", typeof(int));
dt2.Columns.Add("DeptId", typeof(int));
dt2.Columns.Add("FullName", typeof(string));
dt2.Columns.Add("DepartmentName", typeof(string));
dt2.Constraints.Add("PkEmployee", dt2.Columns["EmpId"], true);

ds.Relations.Add(dt1.Columns["DeptId"], dt2.Columns["DeptId"]);
dt2.Columns["DepartmentName"].Expression = "Parent.Description";

dt1.Rows.Add(1, "Finance");
dt1.Rows.Add(2, "IT");
dt2.Rows.Add(1, 2, "Baavgai");

System.Diagnostics.Debug.WriteLine(ds.GetXml());

Results:

<NewDataSet>
  <Deparment>
    <DeptId>1</DeptId>
    <Description>Finance</Description>
  </Deparment>
  <Deparment>
    <DeptId>2</DeptId>
    <Description>IT</Description>
  </Deparment>
  <Employee>
    <EmpId>1</EmpId>
    <DeptId>2</DeptId>
    <FullName>Baavgai</FullName>
    <DepartmentName>IT</DepartmentName>
  </Employee>
</NewDataSet>