IMAT1604: Visual Web Development
DatabaseQuery Code - Constructors
In C# the name of the Constructor method is the same as the
class name, the constructor does not have a return type.
DatabaseQuery has two constructors, the constructor without
a parameter assumes that the database connection string is
called AddressBookDbConnectionString.
The other constructor is the one that will be used more
often as it creates a connection to any database given
the appropriate connection string name.
DatabaseQuery myQuery = new DatabaseQuery("WinesDbConnectionString");
C# DatabaseQuery Class
DatabaseQuery Code - AddParameter
This method needs to be called once for each SQL Parameter
in the stored procedure query. The parameters must be added
in the correct order. With an INSERT query there will one
SQL Parameter for each field in the record, whereas the
simplest SELECT query might have no parameters.
C# DatabaseQuery Class
DatabaseQuery Code - ExecuteSelect()
The code to execute SELECT stored procedures is simpler than
the code needed for update queries. The database connection
is opened, and a DataAdaptor is used to fill the DataTable
with the records retrieved by the SELECT stored procedure.
The database connection is automatically closed at the end
of the Using block.
C# DatabaseQuery Class
DatabaseQuery Code - ExecuteUpdate()
To execute an Update query, an SQLCommand object is
required based on the database connection and the
required stored procedure. Any SQL parameters in
the parameter list have to be added to the command
parameters before the command is executed. If the
command executes sucessfully then the parameter list
is cleared.
C# DatabaseQuery Class
There is a deliberate mistake in this DatabaseQuery class.
What is it? Answer.