Tag Archives: database

IDS ( Intrusion Detection System) yani saldırı tespit sistemi ve IPS (Intrusion Prevention System) ise saldırı önleme sistemi anlamına gelmektedir.Bu tip firewall’lara paket süzen güvenlik duvarı da denmektedir.Son zamanlarda artış gösteren ve ciddi zararlara yol açan hacking saldırılarının yakalanmasına ve önlenmesinde çok önemli rol oynamaktadırlar.IDS,sadece ağdaki kötü niyetli bağlantıları tespit eder ve loglar.IPS ise ağdaki kötü niyetli bağlantıları tespit eder …

Molina_Ullman_-_Database_Systems_-_The_Complete_Book__Prentice__2002_.pdf dosyayı indir

Step 0 – Analyze • Analyze the domain – Learn what things the system is intended to handle. – Learn what the constraints of the domain are. • Analyze the system – Learn what the system is intended to do, what operations it should perform. • We’ve partly done part of this for you… Step 1 – Design • Design …

Typical (abstract) costs • Some typical costs of disk accessing for database operations on a relation stored over n blocks: – Query the full relation: n (disk operations) – Query with the help of index: k, where k is the number of blocks pointed to (1 for key). – Access index: 1 – Insert new value: 2 (one read, one …

Setting • DBMS must allow concurrent access to databases. – Imagine a bank where account information is stored in a database not allowing concurrent access. Then only one person could do a withdrawal in an ATM machine at the time – anywhere! • Uncontrolled concurrent access may lead to problems. lecture11.pdf dosyayı indir

  lecture10.pdf dosyayı indir

Summary – Modifications • Modifying the contents of a database: – Insertions INSERT INTO tablename VALUES tuple – Deletions DELETE FROM tablename WHERE test over rows – Updates UPDATE tablename SET attribute = value WHERE test over rows Insertions with queries • The values to be inserted could be taken from the result of a query: – Example: INSERT INTO …

SELECT-FROM-WHERE • Basic structure of an SQL query: SELECT attributes FROM tables WHERE tests over rows SELECT X FROM T WHERE C Aggregation • Aggregation functions are functions that produce a single value over a relation. – SUM, MAX, MIN, AVG, COUNT SELECT MAX(nrSeats) MAX actually has FROM Rooms; SELECT COUNT(*) FROM Lectures WHERE room = ’VR’; lecture8.pdf dosyayı indir

Summary so far • SQL is based on relational algebra. – Operations over relations • Operations for: – Selection of rows (
) – Projection of columns () – Combining tables • Cartesian product (x) • Join, natural join (⋈C, ⋈) lecture7.pdf dosyayı indir

Goals of database design • ”Map” the domain, find out what the database is intended to model. – The database should accept all data that is possible in reality. – The database should agree with reality and not accept impossible or unwanted data. • We accomplish this by making sure that our database captures all the constraints of the domain. …

Work flow • DRAW your diagram of the domain. • TRANSLATE to relations forming a schema • IDENTIFY dependencides from domain! • RELATE the dependencies to the schema, to find more constraints, and to validate your design. lecture5.pdf dosyayı indir

Summary – FDs so far • X
A – X ”determines” A, A ”depends on” X • Trivial FDs, combining RHSs • Computing closures – Attribute closures: X+ – FD set closures: F+ lecture4.pdf dosyayı indir

Functional dependencies (FDs) • X
A – ”X determines A”, ”X gives A” – ”A depends on X” • X is a set of attributes, A is a single attribute • Examples: – code
name – code, period
teacher lecture3.pdf dosyayı indir

The Entity-Relationship approach • Design your database by drawing a picture of it – an Entity-Relationship diagram – Allows us to sketch the design of a database informally (which is good when communicating with customers) • Use (more or less) mechanical methods to convert your diagram to relations. – This means that the diagram can be a formal specification as …

A database is … • Structured • Persistant • Changable • Digital • True to integrity constraints lecture.pdf dosyayı dindir