Monday, 21 September 2015

Freshers ADO.NET Interview Questions and Answers pdf

11 :: What is Delegate?
Delegate is an important element of C# and is extensively used in every type of .NET application. A delegate is a class whose object (delegate object) can store a set of references to methods.

12 :: How do you update a Dataset in ADO.Net and How do you update database through Dataset?
a. Update a dataset;
Dataset ds = new dataset();
SqlDataAdapter adp = new SqlDataAdapter(Query,connection);
Adp.fill(ds);
Again you can add/update Dataset as below
SqlDataAdapter adp1 = new SqlDataAdapter(Query1,connection);
Adp1.fill(ds);

b. Update database through dataset.
SqlCommandBuilder mySqlCommandBuilder = new SqlCommandBuilder(mySqlDataAdapter);
Foreach(datarow dr in ds.table[0].rows)
{
Dr[“column Name”] = “value”;
mySqlDataAdapter.Update(ds);
}

13 :: What are the steps to connect to a database?
1. Create a connection. This requires a connection string, which can be given declaratively or put in a well defined place like the .config files. Advantage of keeping in .config files is that it enables use of Connection Pooling by .Net framework, else even one small change in connection string will cause CLR to think it's not the same connection and will instantiate new connection for other request.
2. Open the connection and keep it open until done, typically done as using (con) { //use }
3. If using connected data model, create a SqlCommand object, decorate it with desired command, command type (stored procedure for eg), add any parameters and their values to the command, and then consume the command by using ExcuteReader or ExecuteScalar. In case of ExecuteReader, we will get back a handle to a fast-forward, read only pointer to the recordset. We can also decorate Command object with multiple recordsets in 2.0 and execute one by one (MARS - Multiple Active Record Sets)
4. If using disconnected data model, create a DataAdapter object, decorate it with desired SELECT, INSERT, UPDATE, DELETE commands, add parameters as necessary and then fill up a DataSet or DataTable using the DataAdapter. Subsequent SQL can be executed using insert, update, delete commands on the dataset.

14 :: How do you connect to SQL Server Database without using sqlclient?
you can connect sql using oledbname space .

15 :: What is Partial class?
A Partial class is a class that can be split into two or more classes. This means that a class can be physically separated into other parts of the class within the same namespace. All the parts must use the partial keyword. All the other classes should also have the same access modifier. At the compile time, all the partial classes will be treated as a single class. Let us list some advantages of having partial classes.

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