31. Which object is used to add a relationship between two DataTable objects?
The DataRelation object is used to add relationship between two DataTable objects.
32. Explain the new features in ADO.NET Entity Framework 4.0.
ADO.NET Entity Framework 4.0 is introduced in .NET Framework 4.0 and includes the following new features:
- Persistence Ignorance - Facilitates you to define your own Plain Old CLR Objects (POCO) which are independent of any specific persistence technology.
- Deferred or Lazy Loading - Specifies that related entities can be loaded automatically whenever required. You can enable lazy loading in your application by setting the DeferredLoadingEnabledproperty to true.
- Self-Tracking Entities - Refers to the entities that are able to track their own changes. These changes can be passed across process boundaries and saved to the database.
- Model-First Development - Allows you to create your own EDM and then generate relational model (database) from that EDM with matching tables and relations.
- Built-in Functions - Enables you to use built-in SQL Server functions directly in your queries.
- Model-Defined Functions - Enables you to use the functions that are defined in conceptual schema definition language (CSDL).
33. What is the difference between the Clone() and Copy() methods of the DataSet class?
The Clone() method copies only the structure of a DataSet. The copied structure includes all the relation, constraint, and DataTable schemas used by the DataSet. The Clone() method does not copy the data, which is stored in the DataSet. The Copy() method copies the structure as well as the data stored in the DataSet.
34. What are the parameters that control most of connection pooling behaviors?
The parameters that control most of connection pooling behaviors are as follows:
-
Connect Timeout
- Max Pool Size
- Min Pool Size
- Pooling
35. How can you add or remove rows from the DataTable object of DataSet?
The DataRowCollection class defines the collection of rows for the DataTable object in a DataSet. TheDataTable class provides the NewRow() method to add a new DataRow to DataTable. The NewRow method creates a new row, which implements the same schema as applied to the DataTable. The following are the methods provided by the DataRowCollection object:
- Add() - Adds a new row to DataRowCollection.
- Remove()- Removes a DataRow object from DataRowCollection.
- RemoveAt() - Removes a row whose location is specified by an index number.
36. What is the use of DataView?
User-defined view of a table is contained in a DataView. A complete table or a small section of table depending on some criteria can be presented by an object of the DataView class. You can use this class to sort and find data within DataTable. The DataView class has the following methods:
- Find() - Finds a row in a DataView by using sort key value.
- FindRows() - Uses the sort key value to match it with the columns of DataRowView objects. It returns an array of all the corresponding objects of DataRowView whose columns match with the sort key value.
- AddNew() - Adds a new row to the DataView object.
- Delete() - Deletes the specified row from the DataView object according to the specified index.
37. Explain in brief DataAdapter class in ADO.NET.
The DataAdapter class retrieves data from the database, stores data in a dataset, and reflects the changes made in the dataset to the database. The DataAdapter class acts as an intermediary for all the communication between the database and the DataSet object. The DataAdapter Class is used to fill a DataTable or DataSetObject with data from the database using the Fill() method. The DataAdapter class applies the changes made in dataset to the database by calling the Update() method.
The DataAdapter class provides four properties that represent the database command:
SelectCommand, InsertCommand, DeleteCommand, and UpdateCommand.