What is the use of command objects?
Command object helps to execute SQL statements. Following are the methods provided by command object: -
ExecuteNonQuery: - Executes insert, update and delete SQL commands. Returns an Integer indicating the number of rows affected by the query.
ExecuteReader: - Executes select SQL statements which can either be in your .NET code or in a stored procedure. Returns a "Datareader" object.
ExecuteScalar: - Executes SQL command and returns only a single value like count, sum, first record etc.
What are Dataset objects?
Dataset is an in memory object with data tables, rows and columns. You can visualize it as in-memory RDBMS. Dataset has the following features:-
- The in memory RDBMS works in a disconnected manner. In other words even if the connection is closed the dataset is still there in memory.
- You can do modification in the in-memory database object and send the final changes to the database.
Below is a simple code snippet which shows how to access a column value. You can see how the full dataset object hierarchy is accessed to get the column value.
See following video on Dataset is a disconnect while datareader is connected: -