Dbms & oracle

Database
A collection of information organized in such a
way that a computer program can quickly
select desired pieces of data

Traditional Database
• Traditional databases are organized by fields,
records, and files
• A field is a single piece of information
• A record is one complete set of fields
• A file is a collection of records

Database Management System
collection of programs that enables you to enter,
organize, and select data in a database
Various functions of DBMS
• Manage the users and keep restrictions over
them
• Enable users to create, modify and access the
data
• Perform maintenance over the database
(Backing up, Performance tuning, etc)

Various DBMS
• dBase
• FoxPro
• MS-Access
• Oracle
• Sybase
• DB2
• MySQL
• SQL Server

Characteristics of good database system
• Good database is identified by ACID properties
• A – Atomicity
• C – Consistency
• I – Isolation
• D - Durability

Atomicity
• Atomicity refers to combining multiple transaction into single
transaction
• A group of transaction can be considered as a atomic (single)
transaction
• So the database system have to do all or do nothing
Example:
A is transferring Rs.1000 to B's account
Steps:
1) Deduct 1000 from A's account balance
2) Add 1000 to B's account balance.
If first step is done and due to some factors 2nd is not done, will lead to
serious error. So we should do all steps or do nothing
Oracle: savepoint, rollback and commit

Consistency
• System will provide the user to define some rules regarding the data.
(eg. Unique Key)
• Once rules defined, they are consistently maintained until the
database is deleted
Oracle: Primary Key, Unique, Not Null, Foreign Key, Cascade

Isolation
• Database systems are accessed by multiple users simultaneously.
• Every request is isolated from each other.
Eg: -
• Single Credit card account having two credit cards.
• Two cards are swiped simultaneously for amount equal to the credit
limit.
• Two requests reach the server simultaneously.
• But the requests are processed one by one (each request is isolated
from another)
Oracle : Record Locks

Durability
• Once data is stored and committed. And it was retrieved at a later
time, durability confirms that we will get the same data which was
stored earlier.
Oracle– Back up and transaction logs

Normalization
• Overall objective on normalization is to reduce redundancy
• Redundancy – Data repeatedly stored
• Normalization recommends to divide the data across multiple tables
to avoid redundancy
• When data is added, altered or deleted in one table it should
maintain the data consistency.
• Three important forms of normalization
1. First normal form (1NF)
2. Second normal form (2NF)
3. Third normal form (3NF)

First Normal Form (1NF)
"The domain of each attribute contains only atomic values, and
the value of each attribute contains only a single value from that
domain"
We Cannot have multiple values for a particular attribute (field) in
a single record
Name Skill
Raj C++, C#, MS SQL
Arun Java, Oracle
Against 1NF
Employee
Name Skill
Raj C++
Raj C#
Arun Java
Arun Oracle
Compliance with 1NF
Employee

Second Normal Form (2NF)
"a table is in 2NF if and only if it is in 1NF and no non-prime
attribute is dependent on any proper subset of any candidate key
of the table"
Prime – Key field used to identify the entire record (eg. Emp ID)
Non – Prime – Field that depends on Prime Key (eg. DOB)
Candidate Key – When two fields combine to form primary key
Against 2NF
Employee
Name Skill Location
Raj C++ Chennai
Raj C# Chennai
Arun Java Bangalore
Arun Oracle Bangalore
Compliance with 2NF
Employee Skill Employee Location
Name Skill
Raj C++
Raj C#
Arun Java
Arun Oracle
Name Location
Raj Chennai
Arun Bangalore

Third Normal Form (3NF)
"the entity is in second normal form and all the attributes in a
table are dependent on the primary key and only the primary
key""
Against 3NF
Employee
Name City PIN
Raj Chennai 600033
Arun Bangalore 400028
Arjun Chennai 600033
Compliance with 3NF
Employee Pin
Name PIN
Raj 600033
Arun 400028
Arjun 600033
PIN City
600033 Chennai
400028 Bangalore
Compliance with 3NF
Pin

Structured Query Language
• SQL is a standard devised by ANSI
• All DBMS will be following the standard and make some little alteration in it
• Four categories of SQL Statements
• DDL– Data Definition Language
• DML– Data Manipulation Language
• DCL– Data Control Language
• TCL– Transaction Control Language
• DRL or DQL – Data Retrieval or Query Language (With respect to user
rights it belongs to DML group)

DDL Statements
• Create/Modify/ Delete the following
• Table
• Views
• TRUNCATE records from a table

Data types
• Fixed Point Number
• NUMBER (<Width>, <Decimal Places>)
Input Data Specified As Stored As
7,456,123.89 NUMBER 7456123.89
7,456,123.89 NUMBER(*,1) 7456123.9
7,456,123.89 NUMBER(9) 7456124
7,456,123.89 NUMBER(9,2) 7456123.89
7,456,123.89 NUMBER(9,1) 7456123.9
7,456,123.89 NUMBER(6)
(not accepted,
exceeds precision)
7,456,123.89 NUMBER(7,-2) 7456100

Data types
Floating point numbers
Data Type Bytes
utilized
Precision
BINARY_FLOAT 4 7 Digits
BINARY_DOUBLE 8 14 Digits

Data types
Date & Time
Data Type Description Range
DATE Gregorian Date 01.01.0001 to 12.31.9999
TIMESTAMP hh:mm:ss[.nnnnnnnnn]

Data types
ASCII String
Data Type Description Maximum
CHAR(n) Fixed length string of total
length 'n'
2000 Ascii characters
VARCHAR(n) Variable length string 4000 Ascii characters

Data types
Unicode String
Data Type Description Maximum
NCHAR(n) Fixed length string of total
length 'n'
2000 Unicode characters
NVARCHAR(n) Variable length string 4000 Unicode characters

Create a Table
Usage:
CREATE TABLE <Table name> (
<FieldName1> <DataType> [<Constraint>],
<FieldName2> <DataType> [<Constraint>],
.
.
<FieldNameN> <DataType> [<Constraint>])

Create a Table
Constraints
NOT NULL --------- Don't Allow a null value.
UNIQUE --------- Values cannot be duplicated but it can allow one
null value
PRIMARY KEY --------- Values cannot be duplicated and even null is not
allowed.
CHECK ---------- Check for a condition
DEFAULT ----------- Set a default value if user don't provide a value

Create a Table…
Example
CREATE TABLE TblEmployee (
EmpID NUMBER(3) PRIMARY KEY,
EmpFName VARCHAR2(20) NOT NULL,
EmpMName VARCHAR2(20),
EmpLName VARCHAR2(20) NOT NULL);

Create a Table with named constraint
EmpID NUMBER(3) CONSTRAINT pkEmpID PRIMARY KEY,
EmpFName VARCHAR (20) NOT NULL,
EmpMName VARCHAR (20),
EmpLName VARCHAR (20) NOT NULL);
------- OR --------
EmpID NUMBER(3),
EmpFName VARCHAR2(20) NOT NULL,
EmpMName VARCHAR2(20),
EmpLName VARCHAR2(20) NOT NULL,
CONSTRAINT pkEmpID PRIMARY KEY(EmpID)
);
Declare at Column Level
Declare at Table Level

Foreign Key Constraint
CREATE TABLE TblDept (
DeptID NUMBER(3) PRIMARY KEY,
DeptName VARCHAR2(20) NOT NULL);
CREATE TABLE TblEmp(
EmpID NUMBER(3),
EmpName VARCHAR2(30),
DeptID NUMBER(3) DEFAULT 0,
CONSTRAINT pkEmpID PRIMARY KEY(EmpID),
CONSTRAINT fkDeptID
FOREIGN KEY (DeptID) REFERENCES TblDept(DeptID));
Default Constraint, DeptID
is set to 0 if no value
specified

Foreign Key Constraint…
DeptID DeptName
0 Unassigned
1 PRODUCTION
2 PURCHASE
3 SALES
4 HUMAN RESOURCES
Insert the following records in TblDept
Try to insert the value 5 for DeptID in TblEmp (See the error message)
Now insert the following values
EmpID EmpName DeptID
101 Andrews 1
102 James 3
103 Chris 4
104 Johnty 2
105 Johnson 3

Now Delete 104 from the Table TblEmp (It won't affect the Table TblDept)
101 Andrews 1
102 James 3
103 Chris 4
105 Johnson 3
DeptID DeptName
0 Unassigned
1 PRODUCTION
2 PURCHASE
3 SALES
4 HUMAN RESOURCES

Now Delete 3,Sales Department from the table TblDept
(Cannot be deleted as It is referred by TblEmp)
But 2, Purchase Department can be deleted as it don't have any reference.
101 Andrews 1
102 James 3
103 Chris 4
105 Johnson 3
DeptID DeptName
0 Unassigned
1 PRODUCTION
2 PURCHASE
3 SALES
4 HUMAN RESOURCES

ON DELETE CASCADE -------- All the records referring will get deleted
ON DELETE SET NULL -------- Referring Field will set to NULL
ON DELETE SET DEFAULT -------- Default value is assigned

ON DELETE CASCADE
ALTER TABLE TblEmp DROP CONSTRAINT fkDeptID
GO
ALTER TABLE TblEmp ADD CONSTRAINT
fkDeptID FOREIGN KEY (DeptID) REFERENCES TblDept(DeptID)
ON DELETE CASCADE
Now if 3,Sales Department is deleted from the table TblDept, All the
employees belonging to sales department are deleted.
101 Andrews 1
102 James 3
103 Chris 4
105 Johnson 3
DeptID DeptName
0 Unassigned
1 PRODUCTION
2 PURCHASE
3 SALES
4 HUMAN RESOURCES

ON DELETE SET NULL
GO
ON DELETE SET NULL
Now if 3,Sales Department is deleted from the table TblDept, All the values 3 in
DeptID is set to NULL.
101 Andrews 1
102 James NULL
103 Chris 4
105 Johnson NULL
DeptID DeptName
0 Unassigned
1 PRODUCTION
2 PURCHASE
3 SALES
4 HUMAN RESOURCES

ON DELETE SET DEFAULT
GO
ON DELETE SET DEFAULT
Now if 3,Sales Department is deleted from the table TblDept, All the values 3 in
DeptID is set to default value (0).
101 Andrews 1
102 James 0
103 Chris 4
105 Johnson 0
DeptID DeptName
0 Unassigned
1 PRODUCTION
2 PURCHASE
3 SALES
4 HUMAN RESOURCES

Check Constraint
CREATE TABLE TblStudent(
RegNo Int PRIMARY KEY,
StudName Char(20) NOT NULL,
Mark NUMBER(3),
CONSTRAINT chkMark CHECK (Mark>=0 AND Mark <=100)
)
Mark field can take the
values only between 0 and
100

Alter Table
• Add a Column/Constraint
• Alter a Column (Constraint cannot be altered)
• Drop a Column/ Constraint
Add Column
ALTER TABLE TblEmp ADD EmpDOB DATE
or
ALTER TABLE TblEmp ADD (EmpDOB DATE,EmpDOJ DATE)
Alter Column
ALTER TABLE TblEmp MODIFY EmpName VARCHAR2(40)
Drop Column
ALTER TABLE TblEmp DROP COLUMN EmpDOB

Drop Table
Delete the entire table
Usage:
DROP TABLE <Table Name>
Eg.
DROP TABLE TblEmp
Warning
Table cannot be recovered

DML Statements
• Add records to the table (INSERT)
• Modify the record (UPDATE)
• Remove the record from the table (DELETE, TRUNCATE(DDL))
• Retrieve Information from a table (SELECT)

INSERT
INSERT INTO <TableName>(<Field1>, <Field2>,……..<Fieldn>)
VALUES(<Value1>,<Value2>,……<Valuen>)
• Field1 Value1, Field2 Value2 ….. Fieldn Valuen
• Data type of value and field should be matched
• Unspecified Fields will take NULL value or DEFAULT value as per table design
• If Constraint doesn't allow a NULL value for a unspecified field the record is not
inserted
Alternative version:
INSERT INTO <TableName> VALUES(<Value1>,<Value2>,……<Valuen>)
• Values are specified in the same order as that of table's fields order
• Number of values should be exactly matched

INSERT
Create the table
CREATE TABLE TblProduct (ProdID NUMBER(3), ProdName VARCHAR2(20),
LaunchDate Date, Unit VARCHAR2(5),
PricePerUnit NUMBER(9,2))
Insert Record
INSERT INTO TblProduct (ProdID,ProdName,LaunchDate,Unit,PricePerUnit)
VALUES(1,'Lavera',TO_DATE('01-Jan-1998'),'50g',1.15)
Or
INSERT INTO TblProduct VALUES(2,'Lavera',TO_DATE('22-May-2001'),'100g',1.95)

UPDATE
UPDATE <TableName> SET <Field Name1>= <Value1>,
<Field Name2>=<Value2>,
.
.
<Field Name3>=<Value3>
WHERE <Condition>
Warning:
If you exclude the WHERE condition, Entire records will take the given value
Example
Set the cost of Product 5 as $1.65
UPDATE TblProduct SET PricePerUnit=1.65 WHERE ProdID=5
Increase the cost of all products by 15 Cents
UPDATE TblProduct SET PricePerUnit=PricePerUnit+0.15

DELETE
DELETE FROM <TableName> WHERE <Condition>
Warning:
DELETE FROM <TableName> (Without WHERE condition) will delete all the records
Example
Delete Product 6
DELETE FROM TblProduct WHERE ProdID=6
Delete all record
DELETE FROM TblProduct
Use TRUNCATE to delete all records
TRUNCATE TABLE TblProduct
DROP TABLE will delete entire table
But TRUNCATE will delete only the records

DELETE vs TRUNCATE
S No. TRUNCATE DELETE
1 DDL Command DML Command
2 Locks the entire table before
deletion
Locks row by row to delete each record
3 WHERE Condition cannot be used WHERE can be used to selectively
delete the records
4 Never activates a TRIGGER Activates TRIGGER ever deletion of a
row
5 No. of Transactions=1 No of Transactions= No. of rows
deleted
6 High speed process Slow process

INDEX
• Indexes are background objects that are used to retrieve the data fast
• Updating the records slows down as the process involves updating the index
Usage:
CREATE INDEX <Index Name> ON <TableName>
(<Field1> [ASC|DESC],
<Field2>[ASC|DESC],
…
<Fieldn>[ASC|DESC])
Example
CREATE INDEX IdxEmpName ON TblEmp(EmpLName, EmpFName)
DROP an INDEX
DROP INDEX <Index Name> ON <Table Name>

SELECT
CREATE TABLE TblEmpDemo ( EmpID NUMBER(3), EmpFName
VARCHAR2(25), EmpLName VARCHAR2(25), Gender CHAR(1), DOB
Date, DOJ Date, PayPerDay NUMBER(9,2), EmpCity VARCHAR2 (20));

SELECT
INSERT INTO TblEmpDemo VALUES (1, 'Sebastien', 'Porter', 'M', TO_DATE('21-Dec-1974'), TO_DATE( '01-Mar-1999'),
100, 'Austin');
INSERT INTO TblEmpDemo VALUES (2, 'Suzie', 'Hoak', 'F', TO_DATE( '26-Jul-1978'), TO_DATE( '15-Feb-2007') , 80,
'Denver');
INSERT INTO TblEmpDemo VALUES (3, 'Antoinette', 'Clark', 'M', TO_DATE( '07-Aug-1977') , TO_DATE( '23-Mar-2010'),
110, 'New York');
INSERT INTO TblEmpDemo VALUES (4, 'Koko', 'Domba', 'M', TO_DATE( '01-May-1984'), TO_DATE( '01-May-2011'), 85 ,
'Austin');
INSERT INTO TblEmpDemo VALUES (5, 'Janet ', 'West' , 'F', TO_DATE( '14-Jan-1981') , TO_DATE( '12-Dec-1999'), 90,
'Houston');
INSERT INTO TblEmpDemo VALUES (6, 'Catherine', 'Chang', 'F', TO_DATE( '11-Apr-1979') , TO_DATE( '12-Dec-1980'),
100 , 'New York');
INSERT INTO TblEmpDemo VALUES (7, 'Nehemiah', 'Den', 'M', TO_DATE( '05-Dec-1975') , TO_DATE( '05-Jan-1994') ,120,
'Austin');
INSERT INTO TblEmpDemo VALUES (8, 'Sherryl' , 'Dsouza', 'F', TO_DATE( '08-May-1991'), TO_DATE( '03-Feb-2011'), 75,
'New York');
INSERT INTO TblEmpDemo VALUES (9, 'Santos', 'Pacheco', 'M', TO_DATE( '03-Jun-1985'), TO_DATE( '12-Jan-2005'), 90,
'Denver');
INSERT INTO TblEmpDemo VALUES (10, 'Ruby', 'DeGaram', 'F', TO_DATE( '01-Jun-1982'), TO_DATE( '01-Apr-2004'),
110, 'Houston');
INSERT INTO TblEmpDemo VALUES (11, 'Carole', 'Chance', 'F', TO_DATE( '05-Feb-1990'), TO_DATE( '05-Jan-2010'), 80,
'Houston');
INSERT INTO TblEmpDemo VALUES (12, 'Justin', 'Vittas', 'M', TO_DATE( '27-Jun-1983'), TO_DATE( '24-Jun-2004'), 100,
'New York');

SELECT
Usage: (Simple Version)
SELECT <FieldName1> [AS <Alias1>],
<FieldName2> [AS <Alias2>],
.
.
<FieldNamen> [AS <Aliasn>] FROM <Table Name>

SELECT
Select all rows and all columns form the table
SELECT * FROM TblEmpDemo

SELECT
Select all rows and specified columns with alias
SELECT EmpID AS "Emp ID", EmpFName || EmpLName AS Name, DOB, DOJ,
EmpCity AS City FROM TblEmpDemo

SELECT
Print the salary table for a month having 23 working days
SELECT EmpID AS "Emp ID",
EmpFName AS Name,
PayPerDay*23 AS Payable FROM TblEmpDemo

SELECT
Usage: (Filtering records using WHERE)
.
<FieldNamen> [AS <Aliasn>] FROM <Table Name> WHERE <Condition>
Operators Allowed in the WHERE Clause
Operator Description
= Equal
<> Not equal
> Greater than
< Less than
>= Greater than or equal
<= Less than or equal
BETWEEN Between an inclusive range
LIKE Search for a pattern
IN To specify multiple possible values for a column

SELECT
Select Employees whose PayPerDay is more than 100 dollars
SELECT * FROM TblEmpDemo WHERE PayPerDay >= 100

SELECT
Select Employees who are from Austin
SELECT * FROM TblEmpDemo WHERE EmpCity = 'Austin'

SELECT
Select Employees who are not from Austin
SELECT * FROM TblEmpDemo WHERE EmpCity <> 'Austin'

SELECT
Select Employees who joined between the fiscal year 2003-04
SELECT * FROM TblEmpDemo WHERE DOJ BETWEEN TO_DATE('01-Oct-2003') AND
TO_DATE('30-Sep-2004')

SELECT
Select Employees whose first name starting with S
SELECT * FROM TblEmpDemo WHERE EmpFName LIKE 'S%'

SELECT
Select Employees whose first name having second letter a
SELECT * FROM TblEmpDemo WHERE EmpFName LIKE '_a%'

SELECT
Select Employees whose first name having second letter a
SELECT EmpFName,EmpCity FROM TblEmpDemo
WHERE EmpCity IN ('Denver','Houston')
EMPFNAME EMPCITY
------------------------- --------------------
Suzie Denver
Janet Houston
Santos Denver
Ruby Houston
Carole Houston

SELECT
SELECT (ORDER BY)
Usage: (Grouping records using ORDER BY)
.
<FieldNamen> [AS <Aliasn>] FROM <Table Name> ORDER BY <FieldName>
[ASC|DESC]

SELECT
Select Employees in the order of DOB (Eldest first)
SELECT * FROM TblEmpDemo ORDER BY DOB

SELECT
Select Employees in the order of DOB (Youngest First)
SELECT * FROM TblEmpDemo ORDER BY DOB DESC

SELECT
Select Employees in the order of PayPerDay and DOJ (If PayPerDay is repeated
then it uses the DOJ to select the next record)
SELECT * FROM TblEmpDemo ORDER BY PayPerDay, DOJ

SELECT
SELECT DISTINCT
Usage: (Delist the duplicate value)
SELECT DISTINCT <FieldName1> [AS <Alias1>],
.
<FieldNamen> [AS <Aliasn>] FROM <Table Name>

SELECT
List all the cities from which our Employees from
SELECT DISTINCT EmpCity FROM TblEmpDemo
List all the cities from which our Employees from and also separate gender wise
SELECT DISTINCT EmpCity, Gender FROM TblEmpDemo
From Austin and Houston, We have only MALE Employee(s)
From Denver and New York, Both MALE and FEMALE exists

SELECT
SELECT (Using function)
• COUNT - Count the records with respect to some condition
• SUM - Applied for a numerical field, to sum the existing values
• AVG - Compute the average of all the values
• MIN - Find the minimum value of a field
• MAX - Get the maximum

SELECT
Count all the employees we have
SELECT COUNT(*) AS EmpCount FROM TblEmpDemo
Count all the Male employees we have
SELECT COUNT(*) AS MaleEmpCount FROM TblEmpDemo WHERE Gender='M'
Count the total number of cities we have employees from
SELECT COUNT(DISTINCT EmpCity) AS CityCount FROM TblEmpDemo

SELECT
Find total amount paid all the employees per day
SELECT SUM(PayPerDay) AS TotalPay FROM TblEmpDemo
Find the average pay of male employees
SELECT AVG(PayPerDay) AS MaleAvgPay FROM TblEmpDemo WHERE Gender='M'
Find the Max pay
SELECT MAX(PayPerDay) AS MaxPay FROM TblEmpDemo

SELECT
SUB-QUERIES or NESTED QUERIES
A query that exists within another query is called subquery
A subquery nested in the outer SELECT statement has the following components:
• A regular SELECT query including the regular select list components.
⁻ Using a SELECT statement as a column name
• A regular FROM clause including one or more table or view names.
⁻ Getting Data from multiple tables, similar to JOINS
⁻ Also known as EQUI JOIN
• An optional WHERE clause.
⁻ Using SELECT statement in the WHERE clause
• An optional GROUP BY clause.
• Using Aggregate function in columns and group by a particular field
• An optional HAVING clause
• Further filter the result after applying the GROUP BY clause

SELECT
CREATE TABLE AccMaster( AccNo Char(5),
FName VARCHAR2(25), LName VARCHAR2 (25),
Gender CHAR(1),
RefAccNo CHAR(5),
OpenDate DATE,
CurrBal NUMBER(9,2),
CONSTRAINT pkAccNo PRIMARY KEY(AccNo));
CREATE TABLE AccTrans(
TransID NUMBER(5),
TransDate DATE,
AccNo CHAR(5),
Amount NUMBER(9,2), TransType CHAR(1),
CONSTRAINT pkTransID PRIMARY KEY(TransID),
CONSTRAINT fkAccNo FOREIGN KEY(AccNo)
REFERENCES AccMaster(AccNo));

SELECT
INSERT INTO AccMaster VALUES ('56001', 'James', 'Carlton', 'M', NULL,
TO_DATE('05-Oct-2005'),1500);
INSERT INTO AccMaster VALUES ('56002','Chrissy','Arlene','F','56001', TO_DATE('04-
Jan-2006'),1200);
INSERT INTO AccMaster VALUES ('56003','Eldridge','Powers','M','56001',
TO_DATE('24-Jul-2006'),1700);
INSERT INTO AccMaster VALUES ('56004', 'Hobert', 'Spampinato', 'M', '56002',
TO_DATE('21-Feb-2007'),1300);
INSERT INTO AccMaster VALUES('56005','Gloria','Wright','F','56003', TO_DATE('07-
Apr-2008'),1900);

SELECT
INSERT INTO AccTrans VALUES (1, TO_DATE('05-Oct-2005'),'56001',500,'D');
INSERT INTO AccTrans VALUES (2, TO_DATE('01-Dec-2005'),'56001',1500,'D');
INSERT INTO AccTrans VALUES (3, TO_DATE('04-Jan-2006'),'56002',2000,'D');
INSERT INTO AccTrans VALUES (4, TO_DATE('05-Feb-2006'),'56001',400,'W');
INSERT INTO AccTrans VALUES (6, TO_DATE('24-Jul-2006'),'56003',1000,'D');
INSERT INTO AccTrans VALUES (7, TO_DATE('15-Aug-2006'),'56001',100,'W');
INSERT INTO AccTrans VALUES (8, TO_DATE('29-Aug-2006'),'56002',200,'D');
INSERT INTO AccTrans VALUES (9, TO_DATE('12-Sep-2006'),'56003',300,'W');
INSERT INTO AccTrans VALUES (10, TO_DATE('23-Dec-2006'),'56002',800,'W');
INSERT INTO AccTrans VALUES (11, TO_DATE('21-Feb-2007'),'56004',2000,'D');
INSERT INTO AccTrans VALUES (12, TO_DATE('10-Mar-2007'),'56004',200,'W');
INSERT INTO AccTrans VALUES (13, TO_DATE('01-Apr-2008'),'56004',1000,'D');
INSERT INTO AccTrans VALUES (14, TO_DATE('07-Apr-2008'),'56005',100,'D');
INSERT INTO AccTrans VALUES (16, TO_DATE('01-May-2009'),'56005',100,'D');
INSERT INTO AccTrans VALUES (17, TO_DATE('01-Jan-2010'),'56005',700,'D');

SELECT
Include the sub-query as a list component
List all the account holders name along with the referrers name.
SELECT A.AccNo,A.FName,
(SELECT B.FName FROM AccMaster B WHERE A.RefAccNo = B.AccNo)
FROM AccMaster A

SELECT
SELECT query involving more than one table
List all the Transactions and also include the account holder name.
SELECT A.TransID ,A.AccNo,B.FName,A.TransType,A.Amount
FROM AccTrans A,AccMaster B
WHERE A.AccNo=B.AccNo
SELECT AccTrans.TransID
,AccTrans.AccNo,AccMaster.FName,AccTrans.TransType,AccTrans.Amount
FROM AccTrans ,AccMaster
WHERE AccTrans.AccNo=AccMaster.AccNo
SELECT TransID ,AccTrans.AccNo,FName,TransType,Amount
FROM AccTrans ,AccMaster
WHERE AccTrans.AccNo=AccMaster.AccNo
This
technique is
also known
as EQUI JOIN

SELECT
WHERE…IN..
(Check if the value exist in the list)
Find the Employee who is getting highest pay.
SELECT EmpID,EmpFName,PayPerDay FROM TblEmpDemo
WHERE PayPerDay IN (SELECT MAX(PayPerDay) FROM TblEmpDemo)

SELECT
WHERE…NOT IN..
(Check if the value not exist in the list)
Find the Customer who never made any transaction in the year 2006
SELECT AccNo,FName FROM AccMaster WHERE AccNo NOT IN
(SELECT AccNo FROM AccTrans WHERE TO_CHAR(TransDate,'YYYY')='2006')

SELECT
WHERE..ALL/ SOME/ ANY
• A relational operator can be used to compare with…..
• ALL ---- All the values (internally AND operation)
• ANY or SOME ---- At least One value (internally OR operation)
List employees whose salary are above average
SELECT * FROM TblEmpDemo WHERE PayPerDay >=
ALL (SELECT AVG(PayPerDay) FROM TblEmpDemo)

SELECT
GROUP BY & HAVING
GROUP BY clause used to apply an aggregate function (SUM, AVG, MAX..) with
respect to some field
Eg.
Total transaction by each customer (both credit and debit)
SELECT AccNo, SUM(Amount) FROM AccTrans GROUP BY AccNo
WHERE can be used to apply filter before aggregation
Total deposit done by each customer
SELECT AccNo, SUM(Amount) FROM AccTrans
WHERE TransType='D' GROUP BY AccNo
HAVING can be used to apply filter after aggregation
List of customers those who done total deposits more than Rs.1500
SELECT AccNo, SUM(Amount) FROM AccTrans WHERE TransType='D'
GROUP BY AccNo HAVING SUM(Amount) >= 1500

JOINS
JOINS
Inner Join Outer Join
Left Outer
Join
Right
Outer Join
Full Outer
join
Cross join

INNER JOIN
This join returns rows when there is at least one match in both the tables.

INNER JOIN
SalesEmp
EmpID EmpName
1 Hansen
2 Svendson
3 Pettersen
Orders
OrderID OrderNo EmpID
1 77895 3
2 44678 3
3 22456 1
4 24562 1
5 34762 7
SELECT SalesEmp.EmpName, Orders.OrderNo FROM SalesEmp INNER JOIN
Orders ON SalesEmp.EmpID=Orders.EmpID
EmpName OrderNo
Hansen 22456
Hansen 24562
Pettersen 77895
Pettersen 44678

LEFT OUTER JOIN
This join returns all the rows from the left table in conjunction with the matching
rows from the right table. If there are no columns matching in the right table, it
returns NULL values.
If WHERE condition is included saying, right table's column is null then, it will
return only the rows which don't have a match

LEFT OUTER JOIN ….
SalesEmp
EmpID EmpName
1 Hansen
2 Svendson
3 Pettersen
Orders
1 77895 3
2 44678 3
3 22456 1
4 24562 1
5 34762 7
SELECT SalesEmp.EmpName, Orders.OrderNo
FROM SalesEmp LEFT OUTER JOIN Orders ON SalesEmp.EmpID=Orders.EmpID
EmpName OrderNo
Hansen 22456
Hansen 24562
Svendson NULL
Pettersen 77895
Pettersen 44678

LEFT OUTER JOIN.. WHERE NULL
SalesEmp
EmpID EmpName
1 Hansen
2 Svendson
3 Pettersen
Orders
1 77895 3
2 44678 3
3 22456 1
4 24562 1
5 34762 7
FROM SalesEmp LEFT OUTER JOIN Orders ON SalesEmp.EmpID=Orders.EmpID
WHERE Orders.EmpID IS NULL
EmpName OrderNo
Svendson NULL

RIGHT OUTER JOIN
This join returns all the rows from the right table in conjunction with the
matching rows from the left table. If there are no columns matching in the left
table, it returns NULL values.
If WHERE condition is included saying, left table's column is null then, it will
return only the rows which don't have a match

RIGHT OUTER JOIN ….
SalesEmp
EmpID EmpName
1 Hansen
2 Svendson
3 Pettersen
Orders
1 77895 3
2 44678 3
3 22456 1
4 24562 1
5 34762 7
FROM SalesEmp RIGHT OUTER JOIN Orders ON SalesEmp.EmpID=Orders.EmpID
EmpName OrderNo
Hansen 22456
Hansen 24562
Pettersen 77895
Pettersen 44678
NULL 34762

RIGHT OUTER JOIN WHERE NULL ….
SalesEmp
EmpID EmpName
1 Hansen
2 Svendson
3 Pettersen
Orders
1 77895 3
2 44678 3
3 22456 1
4 24562 1
5 34762 7
FROM SalesEmp RIGHT OUTER JOIN Orders ON SalesEmp.EmpID=Orders.EmpID
WHERE SalesEmp.EmpID IS NULL
EmpName OrderNo
NULL 34762

FULL OUTER JOIN
This join combines left outer join and right outer join. It returns row from either
table when the conditions are met and returns null value when there is no match.
If WHERE condition is included saying, left table's or left table's column is null
then, matching records are ignored

FULL OUTER JOIN
SalesEmp
EmpID EmpName
1 Hansen
2 Svendson
3 Pettersen
Orders
1 77895 3
2 44678 3
3 22456 1
4 24562 1
5 34762 7
FROM SalesEmp FULL OUTER JOIN Orders ON SalesEmp.EmpID=Orders.EmpID
EmpName OrderNo
Hansen 22456
Hansen 24562
Pettersen 77895
Pettersen 44678
NULL 34762
Svendson NULL

FULL OUTER JOIN
SalesEmp
EmpID EmpName
1 Hansen
2 Svendson
3 Pettersen
Orders
1 77895 3
2 44678 3
3 22456 1
4 24562 1
5 34762 7
FROM SalesEmp FULL OUTER JOIN Orders ON SalesEmp.EmpID=Orders.EmpID
WHERE SalesEmp.EmpID IS NULL OR Orders.EmpID IS NULL
EmpName OrderNo
NULL 34762
Svendson NULL

CROSS JOIN ….
Alpha
AlphaCol
A
B
C
Numerals
NumCol
1
2
3
SELECT Alpha.AlphaCol,Numerals.NumCol
FROM Alpha CROSS JOIN Numerals
AlphaCol NumCol
A 1
A 2
A 3
B 1
B 2
B 3
C 1
C 2
C 3

UNION & UNION ALL
Alpha
AlphaCol
A
B
C
Numerals
NumCol
1
2
3
SELECT AlphaCol FROM Alpha
UNION
SELECT NumCol FROM Numerals
AlphaCol
A
B
C
1
2
3
Note:
First tables column Name(s) will be taken
UNION will list only distinct values
UNION ALL will list all values even if duplicate exists

Practical Learning(I)
ID Name Age Salary
1 Abe 61 140000
2 Bob 34 44000
5 Chris 34 40000
7 Dan 41 52000
8 Ken 57 115000
11 Joe 38 38000
ID Name City Industry Type
4 Samsonic pleasant J
6 Panasung oaktown J
7 Samony jackson B
9 Orange Jackson B
Number order_date cust_id salesperson_id Amount
10 8/2/96 4 2 540
20 1/30/99 4 8 1800
30 7/14/95 9 1 460
40 1/29/98 7 2 2400
50 2/3/98 6 7 600
60 3/2/98 6 7 720
70 5/6/98 9 7 150
Orders
SalesEmp
Customer

Practical Learning(I)
Write a query to find…
a. The names of all salespeople that have an order with Samsonic.
b. The names of all salespeople that do not have any order with Samsonic.
c. The names of salespeople that have 2 or more orders.

Practical Learning(II)
User
UserID
UserName
PhoneNum
LoginHistory
UserID
LoginDate
1. Write a SQL query that returns the name, phone number and most recent
date for any user that has logged in over the last 30 days
2. Write a SQL query to determine which user had never logged in before

VIEWS
• View is a virtual table that contains columns from one or more tables
• View is an precompiled object, which holds a query.
• It can be used as a table for another query.
• Used to reduce the complexity of large queries
CREATE VIEW EmpOrders
AS
FROM SalesEmp INNER JOIN Orders ON SalesEmp.EmpID=Orders.EmpID

VIEWS
Select VIEW like a table
SalesEmp
EmpID EmpName
1 Hansen
2 Svendson
3 Pettersen
Orders
1 77895 3
2 44678 3
3 22456 1
4 24562 1
5 34762 7
SELECT * FROM EmpOrders
EmpName OrderNo
Hansen 22456
Hansen 24562
Pettersen 77895
Pettersen 44678

PL/SQL
• Programming language of Oracle
• PL/SQL stands for Procedural Language / Structured Query Language
• Developed by oracle to enhance the features of SQL
• PL/SQL Modules can be executed from SQL Plus or even from any front end
(Java)
• Front end developers can expect better performance when compared to
sending a raw DML statement over a network (PL/SQL program is a
precompiled and become a part of database)

PL/SQL
/* Simple PL/SQL program */
DECLARE
message varchar2(20):= 'Hello, World!';
BEGIN
dbms_output.put_line(message);
END;
/

PL/SQL
/* Accessing Tables in PL/SQL */
DECLARE
mProdID TblProduct.ProdID%TYPE;
mProdName TblProduct.ProdName%TYPE;
BEGIN
SELECT ProdID,ProdName INTO mProdID,mProdName FROM
TblProduct WHERE ProdID=2;
dbms_output.put_line('Product ID=' || mProdID || ' Product Name='
|| mProdName);
END;
/
Create variables with
data type compatible
with the table's field
data type

STORED PROCEDURES
• Stored Procedure is a sequence of sql code (program) which can be called
whenever required
• It can take parameters (input/ output)
• When created, it becomes part of the database and pre-compiled
CREATE OR REPLACE PROCEDURE <Procedure Name>
([<Param1> <Data Type> [IN | OUT | IN OUT]]
[<Param2> <Data Type> [IN | OUT | IN OUT]]
….
[<ParamN> <Data Type> [IN | OUT | IN OUT]])
IS
[<Variable1> <Data Type>]
[<Variable2> <Data Type>]
…..
[<VariableN> <Data Type>]
BEGIN
<Code>
END

STORED PROCEDURES
CREATE OR REPLACE PROCEDURE ListCustomer
IS
mAccNo AccMaster.AccNo%type;
mFName AccMaster.FName%type;
mCurrBal AccMaster.CurrBal%type;
CURSOR cAccMaster
IS SELECT AccNo, FName, CurrBal FROM AccMaster;
BEGIN
OPEN cAccMaster;
dbms_output.put_line('Acc No Name Balance');
LOOP
FETCH cAccMaster into mAccNo, mFName, mCurrBal;
EXIT WHEN cAccMaster%notfound;
dbms_output.put_line(mAccNo || ' ' || mFName || ' ' ||
mCurrBal);
END LOOP;
CLOSE cAccMaster;
END;
/
Execute this procedure by
>EXEC ListCustomer

STORED PRCEDURE
Assignment
Consider the banking database
AccMast and AccTrans
Create a procedure called DoTrans taking parameter Account No, Amount, Type
('D'/'W')
• Generate TransID
• Insert record in AccTrans
• Update the AccMast, the current balance of the specified account number

FUNCTIONS
CREATE FUNCTION <Function Name>
([<Param1> <Data Type>],
[<Param2> <Data Type>],
….
[<ParamN> <Data Type>])
RETURNS <Data Type>
AS
BEGIN
<Code>
RETURN <Variable> |<Value>
END;
/

FUNCTIONS
CREATE OR REPLACE FUNCTION totalCustomers
RETURN number
IS
total number(2) := 0;
BEGIN
SELECT count(*) into total FROM AccMaster;
RETURN total;
END;
/
Execute this function by
>select totalcustomers() from dual

STORED PROCEDURE vs FUNCTIONS
Sl. No. Stored Procedure Functions
1 SP can return multiple values Function can return only
one value
2 Transaction is allowed (INSERT/
UPDATE/ DELETE)
Transaction not allowed
3 It can have input & output
parameter
Only input parameter
4 SP can call a function and
another SP
Function can call another
function but not a stored
procedure
5 Exception Handling is
supported
Not supported

TRIGGERS
• Triggers are special kind of stored procedures that executes in response to
certain database action like INSERT/ UPDATE/ DELETE
• Triggers cannot be explicitly invoked like SP or Functions
• Types of Triggers
• BEFORE INSERT|UPDATE|DELETE ---- Fired before the given process
• AFTER INSERT|UPDATE|DELETE ---- Fired after the process

TRIGGERS
Consider an example in the employee table, we are maintaining a separate table for
the relieved, TblOldEmpDemo
CREATE TABLE TblOldEmpDemo (
EmpID NUMBER(3), EmpFName VARCHAR2(25),Gender CHAR(1),DOR DATE)
CREATE OR REPLACE TRIGGER TrgDeleteEmp AFTER DELETE ON TblEmpDemo
FOR EACH ROW
BEGIN
INSERT INTO TblOldEmpDemo VALUES
(:Old.EmpID,:Old.EmpFName,:Old.Gender, SYSDATE);
END;
/

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