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Outlines
File can not be used as distributed computing.
Apply constraint strategy is too difficult.
Database Management System
DBMS contains information about a particular enterprise
Database Applications
Allow the duplication
- File Systems
- —Database Management Systems
- Purpose of Database Systems
- Database Objects
- —Insert data into table
- Database Constraints
File System has duplication
File can not be centralized resource File can not be used as distributed computing.
Apply constraint strategy is too difficult.
Database Management System
DBMS contains information about a particular enterprise
Collection of tables
An environment that is both convenient and efficient to use Database Applications
Banking: all transactions
Airlines: reservations, schedules
Universities: registration, grades
Sales: customers, products, purchases
Online retailers: order tracking, customized recommendations
Manufacturing: production, inventory, orders, supply chain
Human resources: employee records, salaries, tax deductions
Purpose of Database Systems
Database is solution of all drawbacks
— Drawbacks of using file systems to store data:
Separation and isolation of data
Duplication of data.
Data dependence.
Database Objects
How to create database
How to create database
—How to create the tables
How to create fields , records
Example:
Create database dem0;
Examples:
Create database demo;
How to create fields , records
Example:
Create database dem0;
Examples:
Create database demo;
Use demo
Create table emp(id int, name varchar(100))
Create table emp(id int, name varchar(100))
—
Insert the data into table
Insert into emp values(1,’admin’)
Insert into emp values(1,’ali’)Allow the duplication
Database Constraints
To prevent invalid data entry into tables..
1.Primary key
2.Not Null
3.Check
4.Unique
5.Foreign Key
1.Primary key
2.Not Null
3.Check
4.Unique
5.Foreign Key
Constraint Description
NOT NULL: Specifies that the column cannot contain a null value
UNIQUE: Specifies a column or combination of columns whose values must be unique for all rows in the table.
UNIQUE: Specifies a column or combination of columns whose values must be unique for all rows in the table.
PRIMARY KEY: Uniquely identifies each row of the table
FOREIGN KEY: Establishes and enforces a foreign key relationship between the column and a column of the referenced table
CHECK: Specifies a condition that must be true
Example:
sql management studio query
sql management studio query
Create table persons
(p_id int primary key,
first_name varchar(100) not null,
Last_name varchar(100),
Adress varchar(255) unique,
Check(p_id>0))
—
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