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 :
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:
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.
}
Sounds like you just need an update statement:
http://msdn.microsoft.com/en-us/library/bb221186.aspx
You can use the OleDb Provider for this.
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