Data base.ppt

DataBase
What is Data?
 data can be Unprocessed,UnOrganized,Meaningless,raw facts related to any
object in consideration.
 For example your name, age, height, weight, etc are some data related to
you.
 A picture , image , file , pdf etc can also be considered data.
What is Database?
Database is a systematic collection of data.
Databases support storage and manipulation of data.
Each database has one or more distinct APIs for creating, accessing,
managing, searching and replicating the data it holds.
Databases make data management easy. Let's discuss few examples.
An online telephone directory would definitely use database to store
data pertaining to people, phone numbers, other contact details, etc.
Your electricity service provider is obviously using a database to
manage billing , client related issues, to handle fault data, etc.
10/31/2017 1Information Science Dept. DB Lab Class Note

Cont…
What is a Database Management System (DBMS)?
• Database Management System (DBMS) is a collection of programs
which enables its users to access database, manipulate data, reporting
/ representation of data and control access to the database.
Types of DBMS
1. Hierarchical
 It employs the "parent-child" relationship of storing data.
 Its has tree like structure.
 It is rarely used nowadays.
2. Relational DBMS
 It defines database relationships in the form of tables.
 This is the most popular DBMS type in the market.
 Eg:MySQL, Oracle, and Microsoft SQL Server database.
3. Object Oriented Relation DBMS
 It supports storage of new data types.
 The data to be stored is in the form of objects.
 The objects to be stored in the database have attributes(i.e.
gender…) .
 Eg:c++,java,c#,c… etc.

Cont…
What is SQL?
SQL stands for Structured Query language .
• MySQL is a fast, easy-to-use RDBMS being used
for many small and big businesses on the market.
• MySQL is developed,marketed, and supported by
MySQL AB, which is a Swedish company.
• MySQL is becoming so popular .
How can we use MYSQL in Database
Program.

Cont…
MYSQL Exercise
• Use MYSQL Command Line Client provided
by MYSQLServer5.0/MY SQL Query
Browser.
• mysql > SHOW DATABASES;
Creating a database
• mysql > CREATE DATABASE database_name;
Eg: create database Section;

Cont…
Deleting a database
• mysql > DROP DATABASE database_name;
– Eg: Drop database Section;
To select a particular database
• mysql > USE database_name;
– Eg: use section;

Cont…
TO see tables in a database
• mysql >SHOW TABLES;
To create a new table in mysql
• mysql > CREATE TABLE table_name;
– Eg:CREATE TABLE student (id INT(3) NOT NULL PRIMARY
KEY , name VARCHAR(20), address VARCHAR(30), mobile
INT(10));
To see structure of Table in a mysql database
• mysql > DESCRIBE/DESC table_name;
– Eg: desc student;

Cont…
To insert data into a table
• mysql > INSERT INTO table_name;
– Eg:INSERT INTO student (id,Name,Address,Mobile) VALUES (01,
"John", "America","098765431”);
To insert more than one record at once, we can do this,
with each set of field values separated by a comma.
• Mysql>INSERT INTO table_name (column_1, column_2,
column_3, other_value) VALUES (value1, value2, value3, …),
(value1, value2, value3, …), (value1, value2, value3, …);
– Eg:INSERT INTO student VALUES(03,”Teklay
Brhane”,”Axum”,094856095),(04,”Brhane
kfle”,”Mekelle”,0914008514),(…);
To Make a copy of table
– INSERT INTO table_name SELECT * FROM table_name;

Cont…
To See contents inside a table
• mysql > SELECT * FROM table_name;
• Eg:Select * from student;
To Update a record in a table
• mysql > UPDATE table_name SET column1=value,
column2=value2,...
WHERE some_column=some_value;
• Eg: UPDATE student SET name = “John Mc”
WHERE id ='01';

Cont…
To Delete a record from a table
• mysql > DELETE from [table_name] where [column
name]=[field text];
• Eg: delete from student where id=“02”;
To delete all records at the same way from a table
• for slowly deletting data use:
– mysql>delete from table_name;
• for quickly daletting data use:
– Mysql>TRUNCATE TABLE table_name;
• for deletting the hole data from the table:
– Mysql>Delete from table-name;

Cont…
To Add a column in a table
• mysql > ALTER TABLE table_name ADD email
VARCHAR(40) AFTER mobile;
• Eg: ALTER TABLE student ADD email
VARCHAR(40) AFTER mobile;

Cont..
To modify a column in a table
• mysql> ALTER TABLE table_name MODIFY
Column_name Column Definition
• Eg:ALTER TABLE student MODIFY name
varchar(20);
To Change a column in a table
• mysql> ALTER TABLE table_name change Column_name
Column Definition
– Eg:ALTER TABLE student change name F_Nmae
varchar(20);

Cont…
To drop a column in a table
• mysql > ALTER TABLE table_name DROP
column_name
– Eg: ALTER TABLE student DROP
Fname;

SQL Constraints
• SQL constraints are used to specify rules
for the data in a table.
• If there is any violation between the
constraint and the data action, the action is
aborted by the constraint.
• Constraints can be specified when the table
is created (inside the CREATE TABLE
statement) or after the table is created
(inside the ALTER TABLE statement).

Cont…
• In SQL, we have the following constraints:
• NOT NULL - Indicates that a column cannot store NULL
value
• UNIQUE - Ensures that each row for a column must have a
unique value
• PRIMARY KEY - A combination of a NOT NULL and
UNIQUE. Ensures that a column (or combination of two or
more columns) have a unique identity which helps to find a
particular record in a table more easily and quickly
• FOREIGN KEY - Ensure the referential integrity of the
data in one table to match values in another table
• CHECK - Ensures that the value in a column meets a
specific condition
• DEFAULT - Specifies a default value for a column

SQL Not Null
• By default, a table column can hold
NULL values.
• The NOT NULL constraint enforces
a column to NOT accept NULL values.
• Eg: CREATE TABLE Persons
(
P_Id int NOT NULL,
LastName varchar(255) NOT NULL,
FirstName varchar(255),
Address varchar(255),
City varchar(255));

SQL DEFAULT
• To create a Default constraint on creating a table
– Eg: CREATE TABLE Persons
(
P_Id int NOT NULL default”0”,
LastName varchar(255) NOT NULL default”YES”,
FirstName varchar(255),
Address varchar(255),
City varchar(255));
• To create a DEFAULT constraint on the "City" column when the
table is already created, use the following SQL:
• Mysql>alter table table_name alter column_name set default””;
– Eg: ALTER TABLE student ALTER id SET DEFAULT “0”;
• To drop a DEFAULT constraint, use the following SQL:
• Mysql> alter table table_name alter column_name drop default;
– Eg: ALTER TABLE student ALTER id DROP DEFAULT;

SQL Primary Key
• The PRIMARY KEY constraint uniquely
identifies each record in a database table.
• Primary keys must contain UNIQUE
values.
• A primary key column cannot contain NULL
values.
• Most tables should have a primary key, and
each table can have only ONE primary key.

Cont…
• SQL PRIMARY KEY Constraint on CREATE TABLE
– Eg: CREATE TABLE Person(P_Id int NOT NULL,FirstName
varchar(255) NOT NULL,LastName varchar(255),PRIMARY KEY
(P_Id));
• SQL PRIMARY KEY Constraint on ALTER TABLE
• Mysql>alter table table_name add primary key(column_name);
– Eg: Alter table person add primary
key(p_id);
• To DROP a PRIMARY KEY Constraint
• Mysql>Alter table table-name drope primary key;
– Eg: Alter table person drop primary key;

SQL UNIQUE
• The UNIQUE constraint uniquely identifies each record in a
database table.
• SQL UNIQUE Constraint on CREATE TABLE
– Eg: CREATE TABLE Person(P_Id int NOT NULL,FirstName
varchar(255) NOT NULL,LastName varchar(255),UNIQUE
(P_Id));
• SQL UNIQUE Constraint on a already created TABLE
• Mysql> alter table table-name add unique(column_name);
– Eg:Alter table person add unique(FirstName);
• SQL To DROP a UNIQUE Constraint form a database
table
• Mysql> alter table table-name drop index (column_name);
– Eg:ALTER TABLE Person DROP INDEX FirstName;

SQL Foreign Key
• A FOREIGN KEY in one table points to a PRIMARY KEY in another
table
• SQL FOREIGN KEY Constraint on CREATE TABLE
• CREATE TABLE Orders
(
O_Id int NOT NULL,
OrderNo int NOT NULL,
P_Id int,
PRIMARY KEY (O_Id),
FOREIGN KEY (P_Id) REFERENCES Persons(P_Id)
)
• SQL FOREIGN KEY Constraint on ALTER TABLE
• Mysql>alter table table_name add index fk_(column_name);
• Eg: alter table student add index fk_(section);
• To DROP a FOREIGN KEY Constraint
• Mysql>alter table table_name drop index(column_name);
• Eg: ALTER TABLE Orders
DROP FOREIGN KEY fk_PerOrders

Questions???
Field Type Null Key Default Extra
Stu_ID
firstname
lastname
Address
Email
mobile
int (4)
char(15)
char(15)
varchar(50)
varchar(30)
int(10)
NO
NO
YES
YES
YES
YES
PRIM
UNI
MUL
0
NO
YES
YES
YES
YES
Auto increment
1) Create a table called Mytable in database called Mydatabase (given below is definition of table)
2) Enter four rows of data into the tables
3) Delete column from above table
4) Drop primary key from above table
5) Modify column name firstname to fname and lastname to lname
6) Add new column grade after column mobile & make varchar datatype. Set your default
value “NO”. And then insert any value to Mobile column.

• Create table orders like below:
• Create table customers like below:
10/31/2017 Information Science Dept. DB Lab Class Note 22

SQL JOIN
• INNER JOIN: Returns all rows when
there is at least one match in BOTH tables
• LEFT JOIN: Return all rows from the left
table, and the matched rows from the
right table
• RIGHT JOIN: Return all rows from the
right table, and the matched rows from
the left table
• FULL JOIN: Return all rows when there is
a match in ONE of the tables

SQL Inner Join
• The INNER JOIN keyword selects all
rows from both tables as long as there is a
match between the columns in both tables.
• PS! INNER JOIN is the same as JOIN.

SQL Inner Join
• SQL INNER JOIN Syntax
• Mysql>SELECT column_name(s)
FROM table1
INNER JOIN table2
ON table1.column_name=table2.column_name;
• Example
• SELECT Customers.CustomerName, Orders.OrderID
FROM Customers
INNER JOIN Orders
ON Customers.CustomerID=Orders.CustomerID
ORDER BY Customers.CustomerName;

SQL Left Join
• The LEFT JOIN keyword returns all rows
from the left table (table1), with the
matching rows in the right table (table2).
The result is NULL in the right side when
there is no match.
• PS! In some databases LEFT JOIN is called LEFT OUTER
JOIN.

SQL Left Join
• SQL LEFT JOIN Syntax
FROM table1
LEFT JOIN table2
• Example
• SELECT Orders.order_id, Customers.CustomerName,
Orderd.OrderDate
FROM customers
LEFT JOIN orders
ON Orders.customer_id=Customers.customer_id order by
Customers.CustomerName;

SQL Right Join
• The RIGHT JOIN keyword returns all rows
from the right table (table2), with the
matching rows in the left table (table1).
The result is NULL in the left side when
there is no match.
• PS! In some databases RIGHT JOIN is called RIGHT OUTER
JOIN.

SQL RIGHT JOIN
• SQL RIGHT JOIN Syntax
FROM table1
RIGHT JOIN table2
• Example
• SELECT Orders.order_id,
Customers.CustomerName, Orders.OrderDate
• FROM orders
• RIGHT JOIN customers
• ON Orders.customer_id=Customers.customer_id
order by Customers.CustomerName;

SQL Full Join
• The FULL OUTER JOIN keyword
returns all rows from the left table
(table1) and from the right table
(table2).
• PS! FULL OUTER JOIN = LEFT + RIGHT joins.

SQL FULL OUTER JOIN
• SQL FULL OUTER JOIN Syntax
FROM table1
FULL OUTER JOIN table2
• Example
• SELECT Customers.CustomerName,
Orders.OrderID
FROM Customers
FULL OUTER JOIN Orders
ON Customers.CustomerID=Orders.CustomerID
ORDER BY Customers.CustomerName;
•

SQL Union
• The UNION operator is used to
combine the result-set of two or more
SELECT statements.
• Notice that each SELECT statement
within the UNION must have the same
number of columns.
• The columns must also have similar
data types. Also, the columns in each
SELECT statement must be in the
same order.

SQL Union
• SQL UNION Syntax
• Mysql>SELECT column_name(s) FROM table1
UNION ALL
SELECT column_name(s) FROM table2;
• All keyword allows dupicationof values but not union
keyword.
• Example
SELECT customer_id
FROM Customers
union
select customer_id from orders;

Data base.ppt

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Data base.ppt