October 2010 - Posts

• Benefit from Unit Testing T-SQL: Speed up Maintenance of Unit Tests Part Two

  In this post we shall see how adding test data breaks existing unit tests, and how to fix them. This post continues the series on unit testing, the previous posts are How to Benefit from Unit Testing T-SQL: choosing what not to test How to Benefit from Read More... Posted Wednesday, October 27, 2010 5:32 PM by Alexander Kuznetsov | 0 Comments Attachment(s): adding_row.JPG

• Benefit from Unit Testing T-SQL: Speed up Maintenance of Unit Tests

  Once we have a considerable amount of unit tests, their maintenance begins to take noticeable time. If we need to change a module covered by unit tests, it may take less time to make the change itself than to change the corresponding tests accordingly. Read More... Posted Wednesday, October 27, 2010 5:00 PM by Alexander Kuznetsov | 0 Comments Filed under: Database Unit Testing, Unit testing, T-SQL Attachment(s): adding_column.JPG

• Myth Busting: COUNT(*) under REPEATABLE READ may return wrong results

  This came up on sqlservercentral.com, where I read the following claim (in a discussion thread, not in an article): " COUNT(*) is only guaranteed accurate if your isolation level is REPEATABLE READ, SERIALIZABLE, or SNAPSHOT ". I have a repro script which Read More... Posted Thursday, October 21, 2010 12:04 PM by Alexander Kuznetsov | 15 Comments Filed under: Transact SQL, Myth Busting

• Five Years of Writing about SQL Server

  Five years ago I published my first article about SQL Server, "Index Covering Boosts SQL Server Query Performance" It is still quite popular - I just googled up "index covering", and it comes right on top. Bing does the same thing. It was just mentioned Read More... Posted Tuesday, October 19, 2010 3:30 PM by Alexander Kuznetsov | 7 Comments Filed under: SQL Server, Index Covering

• Uncertainty erodes confidence, so add that ORDER BY clause.

  I was reading Eric Lippert's blog post , and came across the following quote: "uncertainty erodes confidence in our users that we have a quality product that was designed with deep thought, implemented with care, and behaves predictably and sensibly". Read More... Posted Monday, October 18, 2010 2:18 PM by Alexander Kuznetsov | 4 Comments Filed under: Transact SQL, Best Practices

• Benefit from Unit Testing T-SQL: Speed up Your Test Harness

  Ideally unit test harness should run very fast. Because all unit testing involving a database is quite slowish, we need to apply some effort to ensure that our tests finish in acceptable time. This slowness might not be a concern when we try out a cool Read More... Posted Friday, October 15, 2010 3:04 PM by Alexander Kuznetsov | 0 Comments Filed under: Database Unit Testing, Unit testing, T-SQL

• Benefit from Unit Testing T-SQL: Reuse Unit Tests as Documentation

  Unit tests provide a very accurate snapshot of what we were thinking about (and what we were missing) when we were writing them. In fact, they are working examples of how we think our code should be used. More to the point, unit tests must be up-to-date, Read More... Posted Thursday, October 14, 2010 1:39 PM by Alexander Kuznetsov | 1 Comments Filed under: Database Unit Testing, Unit testing, T-SQL

• How to Benefit from Unit Testing T-SQL: Exposing Failure in a User-Friendly Way

  Well-written unit tests should succeed only when the module being tested meets the requirements completely.If the test fails, it can do much better than just indicate failure. If the test has managed to provide a clear and comprehensive report of what Read More... Posted Friday, October 08, 2010 2:45 PM by Alexander Kuznetsov | 1 Comments Filed under: Database Unit Testing, Unit testing, T-SQL Attachment(s): diff3.JPG

• How to Benefit from Unit Testing T-SQL: Reusing Manual Tests as Parts of Unit Tests

  In this post we shall see how to incorporate a typical manual test in an automated test harness with minimal effort. Because our goal is to benefit from unit testing, and not to develop as many features as we can think of, we shall concentrate on the Read More... Posted Wednesday, October 06, 2010 9:36 AM by Alexander Kuznetsov | 0 Comments Filed under: Database Unit Testing, Unit testing, T-SQL