What is the use of command objects?
They are used to connect connection object
to Data reader or dataset. Following are the methods provided by command
object:-
•
ExecuteNonQuery: Executes the command defined in the
Command Text property against the connection defined in the Connection property
for a query that does not return any row (an UPDATE, DELETE, or INSERT).
Returns an Integer indicating the number of rows affected by the query.
•
Executes the command defined in the
Command Text property against the connection defined in the Connection
property. Returns a "reader" object that is connected to the
resulting row set within the database, allowing the rows to be retrieved.
•
ExecuteScalar: Executes the command defined in the
Command Text property against the connection defined in the Connection
property. Returns only single value (effectively the first column of the first
row of the resulting row set any other returned columns and rows are discarded.
It is fast and efficient when only a "singleton" value is required
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