Page 94 - DCAP312_WEB_TECHNOLOGIES_II

Web Technologies-II

Notes
The following code accesses the CustomerID column in the first row of the
Customers table
string str;
str=dset.Customers[0].CustomerID;

Untyped Dataset
Untyped dataset is not defined by a schema, instead, you have to add tables, columns, and
other elements to it yourself, either by setting properties at design time or by adding them
at run time. For example : scenario: if you don’t know in advance what the stucture of your
program is that interacting with a component that returns a dataset. the equivalent code above
for Untyped dataset is:
string str;
str=(string)dset.Tables[ “Customers”].Row[0].[ “CustomerID”];
A dataset is a container; therefore, you have to fill it with data.
You can populate a dataset in a variety of ways;

• By using Fill method.
• By creating DataRow objects and adding them to the table’s Rows collection(only at run
time).
• Read an XML document or stream into the dataset.
• Merge (copy) the contents of another dataset.

5.1.3 Display Data in a DataGrid
The Windows Forms DataGrid control displays data in a sequence of rows and columns. The
Windows Forms DataGrid control provides a user interface to ADO.NET datasets. It displays
tabular data and allows for updates to the data source. When you set DataGrid control to a
suitable data source, the control will be automatically populated, creating columns and rows
based on the shape of the data. You can use the DataGrid control for displaying either a single
table or the hierarchical relationships between a set of tables. If you want to work with the
DataGrid control, DataGrid should be bound to a data source by using
• the DataSource and

• DataMember properties at design time
or
• the SetDataBinding method at run time.

Here is the binding to the DataGrid control with DataSet used in this project.
this . dataGrid1 . DataSource = datc . dSet . Tables[ “PersonTable”];
You can only show one table in the DataGrid at a time. If you define a parent-child relationship
between tables, you can navigate between the related tables to select the table you want to
display in DataGrid control.

dset.Relations.Add( “CustomerOrders”,
dset.Tables[ “customers”].Columns[ “CustomerID”],
dset.Tables[ “orders”].Columns[ “CustomerID”]);

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