Chapter 4 Database Security
1. User identity authentication: static password authentication, dynamic password authentication, biometric authentication, smart card authentication
2. Access control mechanism: define user authority and legal authority check.
They together form the access control subsystem of the DBMS
Discretionary Access Control (DAC): Users have different access rights to different database objects, and different users have different rights to the same object, and users can also transfer their access rights to other users.
Mandatory Access Control (MAC): Each database object is marked with a certain level of confidentiality, and each user is also granted a certain level of license. For any object, only users with a legal license can access it.
3. Authorization: Granting and reclaiming
GRANT and REVOKE is to grant or reclaim the operation authority of data to the user
FROM PUBLIC//Recover the authority of all users
FROM U5 CASCADE//Cascade recovery authority
Chapter 5 Data Integrity: Refers to the correctness and compatibility of data
1. Integrity check: non-semantic, incorrect data
Security control: illegal users and illegal operations to prevent illegal access
2. DBMS functions (in terms of integrity maintenance):
(1) Provide a mechanism for defining integrity constraints
(2) Provide methods for integrity checking
(3) Deal with breach of contract
3. Relational DBMS makes integrity control a core support function, thus providing consistent data integrity for all users and applications
. 4. Entity integrity, referential integrity CASCADE
5. User-defined integrity:
attribute constraints Definition: The column value is not empty, the column value is unique, check whether the column value satisfies a conditional expression (CHECK statement)
Note: When inserting a tuple into the table or modifying the value of an attribute, the relational DBMS will check the constraints on the tuple Whether the condition is met, if not, the operation is rejected.
6. Integrity constraint naming clauses
various examples in the self-study book, slightly
Chapter 6 Relational Data Theory
1. Data dependence is a kind of constraint relationship between attributes and attributes within a relationship, and is the correlation between data reflected by the equality of values between attributes. (Functional dependence + multi-value dependence)
2. A good relationship model will not have insert exception, delete exception and update exception , and data redundancy should be as small as possible.
