* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Introduction to ASP.NET
Survey
Document related concepts
Oracle Database wikipedia , lookup
Serializability wikipedia , lookup
Entity–attribute–value model wikipedia , lookup
Microsoft Access wikipedia , lookup
Functional Database Model wikipedia , lookup
Ingres (database) wikipedia , lookup
Extensible Storage Engine wikipedia , lookup
Concurrency control wikipedia , lookup
Microsoft Jet Database Engine wikipedia , lookup
Clusterpoint wikipedia , lookup
Relational model wikipedia , lookup
Microsoft SQL Server wikipedia , lookup
Database model wikipedia , lookup
Transcript
Stored Procedures & User Defined Functions MacDonald Ch. 23 MIS 424 Professor Sandvig Today • Stored Procedures – Store SQL statements on DB • User Defined Functions (UDF) • Database Transactions – Rollback Stored Procedures • So far: – Putting SQL queries in .NET code – Use command object to pass to database • Alternative: – Stored procedures – Store SQL query on database – Call query from .aspx page or business object Stored Procedures • Benefits of SP: – Reusability • Call same SP from many locations in code – Loose coupling • Create clear separation between code & data • Reduces dependencies – Changes in data source do not affect code • N-Tier Programming – Diagram (Source: Microsoft) Benefits of Stored Procedures • Division of duties • Programmers vs. database admin • Security – Set permissions on procedures • Users see only data accessible via procedure Benefits of Stored Procedures • Efficiency – SQL compiled – Execution plan saved • Execute complex procedures – Triggers – Multiple SQL statements – Programming languages • Transact-SQL • .NET languages Disadvantages • More code, greater abstraction • Not fully supported by all databases – MySQL • Recently added • Limited – Microsoft Access • Store basic SQL statements Creating • Visual Studio Creating Syntax & Example Example: • GetTitlesSP.aspx • See handout Views & Functions – Views • “Virtual” tables – No data, definition only • View defined by sql statement • May include data from several tables • Similar to stored procedure except no parameters – Benefits: • Hide table details • Set permissions User Defined Functions • Functions (user defined functions) • Retrieve only • May use parameters • May call from SPs, other functions, SQL commands • Benefits – Reusability – Hide complexity User Defined Functions • Creating in Visual Studio User Defined Functions • Syntax Create FUNCTION dbo.GetProductCategories ( @ProductID int ) RETURNS TABLE AS RETURN Select c.CatLabel FROM tblCategories c, tblProductCategories p where c.CategoryID = p.CategoryID AND p.ProductID = @ProductID sql = "select * from dbo.GetProductCategories(16) order by CatLabel"; Transactions • Many transactions have dependency • Bank transfer – Remove $$ from one account – Add to another • On-line purchase – Charge credit card – Ship item • Item out-of-stock? Transactions If one task fails: • Prior transactions are rolled back • Supported by most commercial databases – Not mySQL • Database keeps a log of transaction • Easy to use • Example: source, output Summary • Advanced Data Techniques – Stored Procedures • Parameters – Transactions • Goal: – Modularity – Reusability – Robust