数据库—第十章.pdf

Chapter 10 Advanced topics in relational databases  Security and user authorization in SQL  Recursion in SQL  Object-relational model 1. User-defined types in SQL 2. Operations on object-relational data  Online analytic processing data cubes Security and user authorization in SQL Authorization Aim:  Make sure users only see the data they‟re suppose to  Guard the database against updates by malicious users How SQL control it?  Authorization ID  Privileges Authorization ID A user is referred to by authorization ID, typically their name.  An element of SQL environment  A user or a group of users who may be granted some particular privileges on objects  User ID: personal security account on behalf of individuals, applications, system services  Not defined in SQL standard regarding its creation,  Role: a defined set of privileges granted to users or other roles  CREATE ROLE  PUBLIC: a special built-in authorization ID  Granting a privilege to PUBLIC makes it available to any authorization ID. Authorization in SQL  File systems identify certain access privileges on files, e.g., read,write,execute.  In partial analogy, SQL identifies nine types of privileges: 1. SELECT = the right to query the relation Authorization in SQL (cont.) 2. INSERT = the right to insert tuples into the relation, may refer to one attribute, in which case the privilege is to specify only one column of the inserted tuple. 3. DELETE = the right to delete tuples from the relation. 4. UPDATE = the right to update tuples of the relation, may refer to one attribute. Other privileges 5. References=the right to refer to that relation in an integrity constraint. 6. Usage=the privilege that applies to several kinds of schema