January 2013 - Posts

• Using constraints to enforce uniqueness of ordered sets of rows

  Even the simplest data integrity rules are not easy to implement in the database if instead of individual rows we need to deal with groups or subsets. For example, making sure that a column value is unique in a table is as trivial as creating a unique Read More... Posted Monday, January 28, 2013 3:10 PM by Alexander Kuznetsov | 2 Comments Filed under: Data Integrity, T-SQL

• The client code that handles timeouts

  After timeouts we need to make sure that active transactions, if any, are rolled back. All timeout handling must be done on the client. This post provides the implementation and unit tests. Implementation The following class extends SqlCommand and rolls Read More... Posted Thursday, January 10, 2013 4:05 PM by Alexander Kuznetsov | 8 Comments Filed under: Defensive programming, T-SQL, Error Handling

• After the timeout

  After the timeout, we may sometimes, but not always, end up with an outstanding transaction. If this is the case, we need to rollback the transaction ourselves. Otherwise the consequent commands which use the same connection might not work as expected. Read More... Posted Wednesday, January 09, 2013 1:23 PM by Alexander Kuznetsov | 2 Comments Filed under: T-SQL, Error Handling, Ado.Net