data abstraction xii_cs for database management cs and ip students .pptx

Data abstraction with foreign key and natural join , equi join difference.

1. Class :XII CS Total strength: 45 Topic : Data base Concepts TLO: Data abstraction levels

2. Data abstraction 04/04/2024

3. Introduction Video games Player plays : not about how scores are stored , what algorithm or steps or codes are there to run this game. How these works on the web.

4. data abstraction entails shielding end-users from unnecessary data. That means  hiding unnecessary background details from the end user to make the accessing of data easy and secure. Ex: fridge : end user uses it without bothering about the microcontrollers inside it Algorithms used to work fridge in different mechanism. Other Examples from students . Source : Youtube https://www.youtube.com/watch?v=GEsVo2fsl0g

5. We just place the order- ecommerce sites We book the tickets . And many more examples are there.

6. Levels of Data Abstraction in DBMS The data abstraction in  DBMS  is implemented in 3 layers: Physical or Internal Level Logical or Conceptual Level View or External Level

7. Physical : how to store data All these racks contain hard disk drives storing all your secured data!  Where the raw data is physically stored as files. This layer contains all the complex data structures and the data accessing methods defined. 

8. Logical level: After taking the raw data from the physical or internal level, the structure of the data is defined at the logical or conceptual level Designing the database /tables . (Schema/structure)

9. View level: many users on the same d/b He/she does not get the entire database, but depending on the queries made from the front-end the user gets to see the data. I

10. Three Important Properties of a Relation Attribute rules: Each attribute in a relation has a unique name. Sequence of attributes in a relation is immaterial. 2. Rules on Tuples: Each tuple in a relation is distinct. Sequence of tuples in a relation is immaterial. 3. R ules on the state of a relation. All data values in an attribute must be from the same domain (same data type). Each data value associated with an attribute must be atomic No attribute can have many data values in one tuple. A special value “NULL” is used to represent values that are unknown or non-applicable to certain attributes.

11. Properties of dbms

12. Domain: domain is a set of values that can be stored in a column of a database table. A domain is usually defined by a column's data type

13. Introduction to Domain Domain constraints in DBMS are the set of rules which defines what kind of attributes can be stored in an entity (a table that stores data)

14. Foreign Key

15. Sql command CREATE TABLE TRANSACTIONS(TRANSACTION_ID INT PRIMARY KEY , AMOUNT FLOAT(6,2) , CUSTOMER_ID INT , FOREIGN KEY(CUSTOMER_ID) REFERENCES CUSTOMERS(CUSTOMER_ID));