You write data validation code in your user interfaces to provide a good user experience. Then you write similar validation code in your services because other clients may not implement those validations in the future. Then you write the same data validations again in the database, well, let's face it, because DBAs are justifiably paranoid about the quality of their data. During this talk, Kevin Hazzard will show you how implement your data validations in a way that they can be shared across all the tiers of your enterprise applications.

1. Enterprise Data Validation Hampton Roads .NET User Group November2009 W. Kevin Hazzard, C# MVP, MCSD.NET

2. Problem Statement Getting your data validation synchronized across all the tiers of an application isn't easy Storing metadata about validations that need to occur as pure data can be less than ideal

3. One Possible Solution Extend SQL Server to support Regular Expression matching Store validation metadata as a set of extended properties in SQL Server Expose your validation metadata as a service

4. What are extended properties? SQL_VARIANT metadata that can be applied to many SQL database objects Examples Add a DATETIME stamp or integer serial number to a table definition to mark its schema version Add Spanish and English description properties to a view as documentation for consumers Add a tag to a public key certificate to record where the private key is escrowed and by whom Add a regular expression to a table's column definition to record the pattern (input mask) that should be used to validate the data

6. Asymmetric Key

7. Assembly

8. Certificate

9. Column*

10. Contract

11. Database

12. Default

13. Event Notification

14. Filegroup

15. File name

16. Schema

17. Service

18. Symmetric Key

19. Synonym

20. Table

21. Trigger

22. Type

23. User

24. View

25. XML Schema Collection

26. Function

27. Message Type

28. Partition Function

29. Partition Scheme

30. Plan Guide

31. Procedure

32. Queue

33. Remote Service Binding

34. Route

35. Rule* Columns aren't objects in SQL server but they can be extended

36. Extended Property Functions sp_addextendedproperty sp_updateextendedproperty sp_dropextendedproperty fn_listextendedproperty sys.extended_properties

37. Adding Extended Properties sp_addextendedproperty [ @name = ] { 'property_name' } [ , [ @value = ] { 'value' } [ , [ @level0type = ] { 'level0_object_type' } , [ @level0name = ] { 'level0_object_name' } [ , [ @level1type = ] { 'level1_object_type' } , [ @level1name = ] { 'level1_object_name' } [ , [ @level2type = ] { 'level2_object_type' } , [ @level2name = ] { 'level2_object_name' }]]] ] Returns 0 (false) for failure or 1 (true) for success.

38. Add Extended Property to Column EXEC sp_addextendedproperty@name = N'Name of the extended property',@value = N'Value of the extended property',@level0type = N'Schema', @level0name = SCHMNAME,@level1type = N'Table', @level1name = TBLNAME,@level2type = N'Column', @level2name = COLNAME;

39. Listing Extended Properties fn_listextendedproperty ( { default | 'property_name' | NULL } , { default | 'level0_object_type' | NULL } , { default | 'level0_object_name' | NULL } , { default | 'level1_object_type' | NULL } , { default | 'level1_object_name' | NULL } , { default | 'level2_object_type' | NULL } , { default | 'level2_object_name' | NULL } ) Table-valued function returning: objtype, objname and name as sysname value as sql_variant

40. Listing Extended Properties for a Column SELECT objtype, objname, name, value FROM fn_listextendedproperty( NULL, 'schema', 'SCHMNAME', 'table', 'TBLNAME', 'column', default );

41. Querying sys.properties SELECT ep.major_id, ep.minor_id, t.name AS [Table Name], ep.name AS [ExtProp Name], c.name AS [Column Name], ep.value AS [Extended Property] FROM sys.extended_properties AS ep INNER JOIN sys.tables AS t ON ep.major_id = t.object_id INNER JOIN sys.columns AS c ON ep.major_id = c.object_id AND ep.minor_id = c.column_id WHERE ep.class = 1;

42. Demonstration 1 Experimenting with SQL Extended Properties

43. Using Regular Expression in SQL Server to Validate Data We can extend SQL Server by adding functions written in C# or Visual Basic The .NET Framework has a great Regular Expressions implementation – let's use it! public class UserDefinedFunctions { [SqlFunction(IsDeterministic = true)] public static SqlBooleanRegexIsMatch( SqlString pattern, SqlString input) { varrex = new Regex(pattern.Value); return rex.IsMatch(input.Value); } };

44. Don't Forget This You must enable the SQL CLR It's disabled by default sp_configure'clr enabled', 1RECONFIGURE WITH OVERRIDEGO

45. Demonsration 2 Adding a SQL CLR User-Defined Function for Regular Expression Matching

46. Pulling It All Together What if we could save regular expressions as metadata to validate our OLTP data? What if we had conventions for storing and accessing that metadata? We could write helper functions that took full advantage of those conventions We could write other kinds of assertions and constraints in the database that depended on them, too We could expose that metadata as a service and use it in multiple application tiers

47. Demonstrations 3 & 4 Baking Validation Into SQL Using Metadata and Constraints Implementing a WCF Service to Expose Validation Metadata

48. For More Information Kevin Hazzard's Bloghttp://tinyurl.com/KevinHazzard Kevin Hazzard'sSlideshare Sitehttp://slideshare.net/wkhazzard Kevin Hazzard'sSpeakerRate Sitehttp://speakerrate.com/wkhazzard Phil Factor's RegEx Functions for SQLCLRhttp://tinyurl.com/dmsmm2