Question

When several fields in a MSAccess table need to be updated (For instance Salary=Salary*Factor, SomeNumber=GetMyBusinessRuleOn(SomeNumber) etc…),and the update should affect every record in a table, which technique would you use?

I have just started to implement this with DataSets, but got stuck (Updating and persisting dataset problem)

But maybe this isn’t even the ideal way to handle this kind of batch update?

Note : the updates don’t have to be on disconnected data first, so a dataset is not necessary.

UPDATE :

• One command won’t do, I need some kind of recordset or cursor to cycle through the records

Answer 1

I would just use a ODBCConnection/ODBCCommand and use a SQL Update query.

There is a JET Database driver that you should be able to use to establish a database connection to a MSAccess database using the ODBCConeection object.

string connectionString = "Provider=Microsoft.Jet.OLEDB.4.0; Data Source=c:\\PathTo\\Your_Database_Name.mdb; User Id=admin; Password=";

using (OdbcConnection connection = 
           new OdbcConnection(connectionString))
{
    // Suppose you wanted to update the Salary column in a table
    // called Employees
    string sqlQuery = "UPDATE Employees SET Salary = Salary * Factor";

    OdbcCommand command = new OdbcCommand(sqlQuery, connection);

    try
    {
        connection.Open();
        command.ExecuteNonQuery();
    }
    catch (Exception ex)
    {
        Console.WriteLine(ex.Message);
    }
    // The connection is automatically closed when the
    // code exits the using block.
}

You could use these websites to help you generate a connection string:

• http://www.connectionstrings.com/
• http://www.sqlstrings.com/

EDIT – Example for using a data reader to cycle through records in order to aply the business rule

I should note that the following example could be improved in certain ways (especially if the database driver supports parameterized queries). I only wanted to give a relatively simple example to illustrate the concept.

using (OdbcConnection connection = 
           new OdbcConnection(connectionString))
{
    int someNumber;
    int employeeID;
    OdbcDataReader dr = null;
    OdbcCommand selCmd = new OdbcCommand("SELECT EmployeeID, SomeNumber FROM Employees", connection);

    OdbcCommand updateCmd = new OdbcCommand("", connection);

    try
    {
        connection.Open();
        dr = selCmd.ExecuteReader();
        while(dr.Read())
        {
            employeeID = (int)dr[0];
            someNumber = (int)dr[1];
            updateCmd.CommandText = "UPDATE Employees SET SomeNumber= " + GetBusinessRule(someNumber) + " WHERE employeeID = " + employeeID;

            updateCmd.ExecuteNonQuery();
        }
    }
    catch (Exception ex)
    {
        Console.WriteLine(ex.Message);
    }
    finally
    {
       // Don't forget to close the reader when we're done
       if(dr != null)
          dr.Close();
    }
    // The connection is automatically closed when the
    // code exits the using block.
}