TAILIEUCHUNG - Hướng dẫn học Microsoft SQL Server 2008 part 72

Tóm tắt Các lớp trừu tượng hóa dữ liệu là một thành phần quan trọng của kế hoạch kiến trúc cơ sở dữ liệu của bạn và nó đóng một vai trò quan trọng trong việc xác định mở rộng trong tương lai và chi phí bảo trì cơ sở dữ liệu. | Part IV Developing with SQL Server Summary The data abstraction layer is a key component of your database architecture plan and it plays a major role in determining the future extensibility and maintenance costs of the database. Even when it seems that the cost of developing a data abstraction layer and refactoring the existing application code to hit the data abstraction layer instead of tables might be prohibitively expensive savvy IT or product managers understand that in the long run it will save money and their job. 672 W I jL . . V - - V -. t Î Q L S j is. . - uA-X fnamic SQL and ode Generation _ -_ Folks laugh when they hear that my favorite project is based on the notion that T-SQL is a great language for code generation. Nordic New Object Relational Design is essentially a code-generation tool that uses dynamic SQL to create tables stored procedures and views. T-SQL works rather well for code generation thank you. The term dynamic SQL has a couple of differing definitions. Some say it describes any SQL query submitted by a client other than a stored procedure. That s not true. SQL submitted from the client is better known as ad-hoc SQL. It s more accurate to say that dynamic SQL describes any SQL DML statement assembled dynamically at runtime as a string and then submitted. Dynamic SQL is very useful for several tasks IN THIS CHAPTER Executing dynamic SQL Parameterized queries The risk of SQL injection Generating stored procedures Alternatives to dynamic SQL Multiple possible query criteria can be dynamically assembled into custom FROM WHERE and ORDER BY clauses for flexible queries. Code can respond to the schema of the database and generate appropriate triggers CRUD stored procedures and views. Dynamic code can auto-generate very consistent stored procedures. However note the following issues when developing dynamic SQL Dynamic SQL that includes user entries in WHERE clauses can be open to SQL injection attacks. .

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