TOP10 DEV SKILLS TO MAKE YOUR DBA HAPPY Kevin Kline Director of Engineering Services, SQL Sentry SQL Server MVP since 2004 Twitter, FB, LI: KEKline Blog:

SQLSentry.net Agenda ToolsTechniques Process, Patterns & Practices Happy & Helpful DBA!

SQLSentry.net #1. Tools: Everybody’s Best Friend Books Online Regular updates available Microsoft® SQL Server™ Management Studio (SSMS) Query plans Object scripting Quick and dirty data browsing Good source control integration

SQLSentry.net #2. Execution Plans and Traces SQL Server processes a query through an execution plan aka a query plan Learn how to compare in SSMS Learn how to watch it happen with SQL Profiler Query performance may be misleading Should evaluate on comparable data sizes Different CPU, Disk, caching, etc. Evaluate the query “Cost”

SQLSentry.net TECHNIQUES

SQLSentry.net #3. Test Harness & Testing Clear your caches Measure: Total elapsed time Individual statement time IO load Facilitates automation of execution plans Get to know the DMV sys.dm_exec_query_stats

SQLSentry.net #4. Query Performance Tips Indexes! Statistics! WHERE clauses: Don’t put a function around an indexed column Can ensure or prevent index usage Use EXISTS to check for existence Be careful: NOT IN clauses Temp variables User-defined functions

SQLSentry.net #5. Sets Versus Rows Microsoft® Visual C#®, Visual Basic®, Visual C++®, etc. are procedural languages Tell the computer what to do SQL is a declarative language Tell the computer what you want Learn to think in terms of sets: One pass through a table Let the computer process joins and filters Loops and cursors for specific use-cases only

SQLSentry.net #6. Connecting to SQL Server Use the SqlClient namespace in Microsoft®.NET Use Connection Pooling On by default in.NET Set Application Name in connection string Helps troubleshooting and monitoring Slightly degrades connection pooling SqlDataReaders are much faster than DataTables Update through stored procedures or SQL statements

SQLSentry.net Example Code to Set the App Name SqlConnectionStringBuilder csb = new SqlConnectionStringBuilder(); csb.DataSource = “L40\YUKON”; csb.IntegratedSecurity = true; csb.InitialCatalog = "AdventureWorks"; csb.ApplicationName = "MyDemoApp"; string connectionString = csb.ToString(); SqlConnection conn = new SqlConnection(); conn.ConnectionString Source=L40\YUKON; Initial Catalog=AdventureWorks; Integrated Security=True; Application Name=MyDemoApp”;

SQLSentry.net #7. Handling Nulls NULLs = ? ANSI SQL-92 requires any comparison to a NULL to fail (i.e. false) This is SET ANSI_NULLS ON default setting NULL = NULL returns false NULL NULL returns false ANSI_NULLS OFF WHERE NULL = NULL returns true How do I know when I don’t know what I know, y’know?

SQLSentry.net Handling Nulls Use WHERE ColumnName IS NULL Avoid WHERE ColumnName = NULL WHERE Col) WHERE IS NULL OR

SQLSentry.net Nulls on the Client Basic types (int, string, etc.) don’t handle Null SqlDataReader IsDBNull tests whether a column is null DataColumn AllowDBNull property System.DBNull.Value Populate SqlParameters Nullable types (int?, string?, etc.) do handle Null Really just Nullable Any type can be declared nullable

SQLSentry.net Nullable Types Classes (types) that support Null Use IsDBNull to check database for NULL string? s; Console.WriteLine(s.HasValue.ToString()); s = “Test”; string? x = null;

SQLSentry.net #8. Transactions and Error Handling Ability to consume T-SQL errors Can nest TRY…CATCH blocks Used in the CATCH block Preventing Errors Use EXISTS() to check for rows Use a return code to signify failure

SQLSentry.net Client-Side Error Handling Catch a SqlException Check the Errors collection for multiple errors try { SqlDataReader r = cmd.ExecuteReader(); } catch (SqlException ex) { Console.WriteLine(ex.Message); Console.WriteLine(ex.Errors.Count.ToString()); }

SQLSentry.net Transactions COMMIT TRAN matches BEGIN TRAN ROLLBACK TRAN cancels ALL transactions Always BEGIN, COMMIT, and ROLLBACK transactions at a consistent level Always test prior to COMMIT or ROLLBACK

SQLSentry.net Client-Side Transactions SqlConnection conn = new SqlConnection(“…") ; conn.Open(); SqlTransaction trans = conn.BeginTransaction(); SqlCommand cmd = new SqlCommand(); cmd.Connection = conn; cmd.Transaction = trans; try { // do some stuff trans.Commit(); } catch (SqlException) { trans.Rollback(); }

SQLSentry.net PATTERNS & PRACTICES

SQLSentry.net #9. Security is NOT an Afterthought SQL Injection is ________________________________. Plan ahead of time to minimize issues: Ensure the least privileges principle for applications running on your servers How much surface area do your servers expose? Who has access to your servers? How do you find out the who, what, and when of a breach?

SQLSentry.net #10. Change Management is RISK Management Understand what the job entails and what makes a DBA successful! Change control is important! Without it, DBAs face: Changes that leave things worse than they started Piecemeal rollbacks that cripple applications Inconsistent support across applications and servers Proper change management means: Processed by a “change management board” composed of all key stakeholders Performed at pre-planned times and within a defined time limit Change is tested and verified to have no effect or positive effect on production environment Changes are isolated, atomic, and reversible 21

SQLSentry.net Additional Resources Plan Explorer Free: server-query-view.asphttp://sqlsentry.net/plan-explorer/sql- server-query-view.asp Twitter and #SQLHelp SQLCAT.com SQLSkills.com Community Sites: SQLPASS.org SQLServerCentral.com SQLBlog.com SQLServerFAQ.com

SQLSentry.net SUMMARY SSMS, Traces, and Execution Plans Test Harness & Testing Query Tuning Tips Temp tables Cursors & Loops NULL Error Handling Transactions Security isn’t an afterthought Change Management is risk management

SQLSentry.net Q & A Send questions to me at: Twitter, Facebook, LinkedIn at KEKline Slides at IT Leadership content at THANK YOU!