Event #3 for DevMix Team

1. Prepared by: Noha Mostafa Bakry Introduction to relational database

2. Where are relational databases? You cannot avoid it and it’s everywhere! You can say it actually makes the current society and your life work! Banking/Credit card /Social Security Info… Online shopping/booking…

6. What are relational databases? A relational database stores all its data inside tables, and nothing more. All operations on data are done on the tables themselves or produces another tables as the result. You never see anything except for tables.

8. Create relational database?

10. To create table must determine field name and data type and select primary key for table which must be unique and used for relations .

11. Table 2 contain ID as foreign key

12. Relation between tables 1-one to one . 2-one to many. 3 – many to many.

13. One to one In one-to-one relationship, two tables are associated in such a way that each record in first table can have only one matching record in second table, and each record in second table can have only one matching record in first table.

15. One to many In one-to-many relationship, two tables are associated in such a way that each record in the first table can have many matching records in second table, but a record in second table has only one matching record in first table.

17. Many to many In many-to-many relationship, two tables are associated in such a way that each record in the first table can have many matching records in second table, and a record in second table can have many matching records in first table.

19. Relation between tables in our example is one to many.

20. What is E-R diagram? Short for entity relationship diagram. Used to represent relations between tables and relation types.

21. What is Query ? A database query is a request for information from a database.

24. There are two goals of the normalization process: 1-eliminating redundant data ( storing the same data in more than one table) . 2- ensuring data dependencies (only storing related data in a table).

27. Remove subsets of data that apply to multiple rows of a table and place them in separate tables.

30. UPDATE PersonsSET Address='Nissestien 67', City='Sandnes'WHERE LastName='Tjessem' AND FirstName='Jakob‘ DELETE FROM PersonsWHERELastName='Tjessem' AND FirstName='Jakob‘

31. Any Questions ?