DBMS information in detail || Dbms (lab) ppt

DBMS (LAB)
SQL/PLSQL
By:-Gourav Kottawar 1

• Introduction of SQL
• DDL, DML, DTL
• Basic Data Types
• Char, varchar/varchar2, long, number,
Fixed & floating point Date, CLOB, BLOB

• What is SQL?
• SQL stands for Structured Query Language
• SQL lets you access and manipulate databases
• SQL is an ANSI (American National Standards Institute)
standard
• What Can SQL do?
• SQL can execute queries against a database
• SQL can retrieve data from a database
• SQL can insert records in a database
• SQL can update records in a database
• SQL can delete records from a database
• SQL can create new databases
• SQL can create new tables in a database
• SQL can create stored procedures in a database
• SQL can create views in a database
• SQL can set permissions on tables, procedures, and views

• SELECT * FROM Persons;
• SQL is not case sensitive, Semicolon after
SQL Statements.
• Some database systems require a semicolon
at the end of each SQL statement.
• Semicolon is the standard way to separate
each SQL statement in database systems
that allow more than one SQL statement to
be executed in the same call to the server.
• We are using MS Access and SQL Server
2000 and we do not have to put a semicolon
after each SQL statement, but some
database programs force you to use it.

• SQL DML and DDL
• SQL can be divided into two parts: The
Data Manipulation Language (DML) and
the Data Definition Language (DDL).
• The query and update commands form the
DML part of SQL:
• SELECT - extracts data from a database
• UPDATE - updates data in a database
• DELETE - deletes data from a database
• INSERT INTO - inserts new data into a
database

• The DDL part of SQL permits database
tables to be created or deleted. It also
define indexes (keys), specify links
between tables, and impose constraints
between tables. The most important DDL
statements in SQL are:
• CREATE TABLE - creates a new table
• ALTER TABLE - modifies a table
• DROP TABLE - deletes a table

• A Transaction Control Language (TCL) :
• is a computer language and a subset of SQL,
used to control transactional processing in a
database. A transaction is logical unit of work that
comprises one or more SQL statements, usually a
group of Data Manipulation Language (DML)
statements.
• Examples of TCL commands include:
• COMMIT to apply the transaction by saving the
database changes.
• ROLLBACK to undo all changes of a transaction.
• SAVEPOINT to divide the transaction into smaller
sections. It defines breakpoints for a transaction to
allow partial rollbacks.

DATA TYPES IN SQL

Data
Type
Syntax Explanation (if applicable)
INTEGER INTEGER(p) Integer numerical (no decimal). Precision p
SMALLINT Integer numerical (no decimal). Precision 5
INTEGER
Integer numerical (no decimal). Precision
10

Syntax
float [ ( n ) ]
Is a floating point number data with the following valid
values: - 1.79E + 308 through -2.23E - 308, 0 and 2.23E
-308 through 1.79E + 308. n is the number of bits used to
store the mantissa of the float number in scientific
notation and thus dictates the precision and storage size.
n must be a value from 1 through 53. The default value of
n is 53.
real
Is a floating point number data with the following valid
values: –3.40E + 38 through -1.18E - 38, 0 and 1.18E -
38 through 3.40E + 38. Storage size is 4 bytes. In SQL
Server, the synonym for real is float(24).

nvalue Precision Storage size
1-24 7 digits 4 bytes
25-53 15 digits 8 bytes
Data type Range Storage
float
- 1.79E+308 to -2.23E-
308, 0 and 2.23E-308
to 1.79E+308
Depends on the value
of n
real
- 3.40E + 38 to -1.18E -
38, 0 and 1.18E - 38 to
3.40E + 38
4 Bytes

character char(x)
Where x is the number of
characters to store. This data
type is space padded to fill the
number of characters
specified.
character
varying
varchar2(x)
Where x is the number of
characters to store. This data
type does NOT space pad.
BOOLEAN BOOLEAN
Stores TRUE or FALSE values
date date
Stores year, month, and day
values.
time time
Stores the hour, minute, and
second values.
timestamp timestamp
Stores year, month, day, hour,
minute, and second values.By:-Gourav Kottawar 12

Difference between VARCHAR
and VARCHAR2
1. VARCHAR is going to be replaced by VARCHAR2 in
next version. So, Oracle suggests the use
VARCHAR2 instead of VARCHAR while declaring
datatype.
2. VARCHAR can store up to 2000 bytes of characters
while VARCHAR2 can store up to 4000 bytes of
characters.
3. If we declare datatype as VARCHAR then it will
occupy space for NULL values, In case of VARCHAR2
datatype it will not occupy any space.

• Difference Between Number and Integer
• NUMBER always stores as we entered. Scale is -84 to 127.
But INTEGER rounds to whole number. The scale for
INTEGER is 0. INTEGER is equivalent to NUMBER(38,0). It
means, INTEGER is constrained number. The decimal place
will be rounded. But NUMBER is not constrained.
INTEGER(12,2) => 12
INTEGER(12.5) => 13
INTEGER(12.9) => 13
INTEGER(12.4) => 12
NUMBER(12,2) => 12.2
NUMBER(12.5) => 12.5
NUMBER(12.9) => 12.9
NUMBER(12.4) => 12.4By:-Gourav Kottawar 14

• Database Tables
• A database most often contains one or
more tables. Each table is identified by a
name (e.g. "Customers" or "Orders").
Tables contain records (rows) with data.
• Below is an example of a table called
"Persons":

P_Id LastName FirstName Address City
1 Hansen Ola Timoteivn 10 Sandnes
2 Svendson Tove Borgvn 23 Sandnes
3 Pettersen Kari Storgt 20 Stavanger
The table above contains three records (one for each person)
and five columns (P_Id, LastName, FirstName, Address, and
City).

• The CREATE TABLE Statement
• The CREATE TABLE statement is used to
create a table in a database.
• SQL CREATE TABLE Syntax
• CREATE TABLE table_name
(
column_name1 data_type,
....
)

• CREATE TABLE Example
• Now we want to create a table called
"Persons" that contains five columns: P_Id,
LastName, FirstName, Address, and City.
• We use the following CREATE TABLE
statement:
• CREATE TABLE Persons
(
P_Id int,
LastName varchar(255),
FirstName varchar(255),
Address varchar(255),
City varchar(255)
);

• The P_Id column is of type int and will hold
a number. The LastName, FirstName,
Address, and City columns are of type
varchar with a maximum length of 255
characters.
• The empty "Persons" table will now look
like this:
• The empty table can be filled with data
with the INSERT INTO statement.

• SQL Constraints
• Constraints are used to limit the type of data that
can go into a table.
• Constraints can be specified when a table is
created (with the CREATE TABLE statement) or
after the table is created (with the ALTER TABLE
statement).
• We will focus on the following constraints:
• NOT NULL
• UNIQUE
• PRIMARY KEY
• FOREIGN KEY
• CHECK
• DEFAULT

• SQL NOT NULL Constraint
• The NOT NULL constraint enforces a column to NOT accept
NULL values.
• The NOT NULL constraint enforces a field to always contain a
value. This means that you cannot insert a new record, or
update a record without adding a value to this field.
• The following SQL enforces the "P_Id" column and the
"LastName" column to not accept NULL values:
(
P_Id int NOT NULL,
LastName varchar(255) NOT NULL,
City varchar(255)
)

• SQL UNIQUE Constraint
• The UNIQUE constraint uniquely identifies
each record in a database table.
• The UNIQUE and PRIMARY KEY
constraints both provide a guarantee for
uniqueness for a column or set of
columns.
• A PRIMARY KEY constraint automatically
has a UNIQUE constraint defined on it.
• Note that you can have many UNIQUE
constraints per table, but only one
PRIMARY KEY constraint per table.

• SQL UNIQUE Constraint on CREATE TABLE
• The following SQL creates a UNIQUE constraint
on the "P_Id" column when the "Persons" table is
created:
• MySQL:
(
P_Id int NOT NULL,
City varchar(255),
UNIQUE (P_Id)
)

(
P_Id int NOT NULL UNIQUE,
City varchar(255)
)

(
P_Id int NOT NULL UNIQUE,
City varchar(255)
)
• To allow naming of a UNIQUE constraint, and for defining a UNIQUE
constraint on multiple columns, use the following SQL syntax:
• MySQL / SQL Server / Oracle / MS Access:
(
P_Id int NOT NULL,
City varchar(255),
CONSTRAINT uc_PersonsId UNIQUE (P_Id,LastName)
)

• SQL UNIQUE Constraint on ALTER TABLE
• To create a UNIQUE constraint on the "P_Id" column
when the table is already created, use the following SQL:
• ALTER TABLE Persons
ADD UNIQUE (P_Id)
• To allow naming of a UNIQUE constraint, and for
defining a UNIQUE constraint on multiple columns, use
the following SQL syntax:
ADD CONSTRAINT uc_PersonID UNIQUE
(P_Id,LastName)

• To DROP a UNIQUE Constraint
• To drop a UNIQUE constraint, use the
following SQL:
• SQL Server / Oracle / MS Access:
DROP CONSTRAINT uc_PersonID

• SQL PRIMARY KEY Constraint
• 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.
• Each table should have a primary key, and
each table can have only one primary key.
• SQL PRIMARY KEY Constraint on
CREATE TABLE

• The following SQL creates a PRIMARY KEY on the "P_Id"
column when the "Persons" table is created:
• MySQL:
(
P_Id int NOT NULL,
City varchar(255),
PRIMARY KEY (P_Id)
)
(
P_Id int NOT NULL PRIMARY KEY,
City varchar(255)
) By:-Gourav Kottawar 29

• SQL PRIMARY KEY Constraint on
ALTER TABLE
• To create a PRIMARY KEY constraint on
the "P_Id" column when the table is already
created, use the following SQL:
• MySQL / SQL Server / Oracle / MS
Access:
ADD PRIMARY KEY (P_Id)

ADD CONSTRAINT pk_PersonID
PRIMARY KEY (P_Id);
• Note: If you use the ALTER TABLE statement to
add a primary key, the primary key column(s)
must already have been declared to not contain
NULL values (when the table was first created).

• To DROP a PRIMARY KEY Constraint
• To drop a PRIMARY KEY constraint, use
the following SQL:
• MySQL:
DROP PRIMARY KEY
DROP CONSTRAINT pk_PersonID

• The FOREIGN KEY constraint SQL FOREIGN
KEY Constraint
• A FOREIGN KEY in one table points to a PRIMARY KEY
in another table.
• Let's illustrate the foreign key with an example. Look at
the following two tables:
• The "Persons" table:

O_Id OrderNo P_Id
1 77895 3
2 44678 3
3 22456 2
4 24562 1
PERSONS TABLE
ORDERS TABLE

35
Note that the "P_Id" column in the "Orders" table points to the
"P_Id" column in the "Persons" table.
The "P_Id" column in the "Persons" table is the PRIMARY
KEY in the "Persons" table.
The "P_Id" column in the "Orders" table is a FOREIGN KEY in
the "Orders" table.
The FOREIGN KEY constraint is used to prevent actions that
would destroy link between tables.
The FOREIGN KEY constraint also prevents that invalid data
is inserted into the foreign key column, because it has to be
one of the values contained in the table it points to.
By:-Gourav Kottawar

• 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)
)

• CREATE TABLE Orders
(
O_Id int NOT NULL PRIMARY KEY,
OrderNo int NOT NULL,
P_Id int FOREIGN KEY REFERENCES
Persons(P_Id)
)

DROP TABLE
• Helps in removing the rows from the table.
• It is a DML command.
• The description (structure) of the table is
removed.
• The existence of the table is removed.
(Table cant be seen from in select * from tab).
Rollback though shows completed but table
view doesn’t come back.
AS IT IS A DML COMMAND ROLLBACK WILL
NOT WORK

• ALTER table tablename
DROP column colname
SQL> alter table emp
2 drop column age;
drop column age
*
ERROR at line 2: ORA-00905: missing
keyword
ALTER-Drop column will work in Oracle 9i
and above version.By:-Gourav Kottawar 39

• ALTER TABLE Orders
ADD FOREIGN KEY (P_Id)
REFERENCES Persons(P_Id);
• ALTER TABLE Orders
ADD CONSTRAINT fk_PerOrders
FOREIGN KEY (P_Id)
REFERENCES Persons(P_Id)

SQL> drop table room;
Table dropped.
SQL> desc room; //description is not
available
ERROR:
ORA-04043: object room does not exist

• The INSERT INTO Statement
• The INSERT INTO statement is used to insert a
new row in a table.
• SQL INSERT INTO Syntax:
• It is possible to write the INSERT INTO
statement in two forms.
• The first form doesn't specify the column names
where the data will be inserted, only their values:
• INSERT INTO table_name
VALUES (value1, value2, value3,...)

• INSERT INTO Persons (P_Id, LastName,
FirstName)
VALUES (5, 'Tjessem', 'Jakob')
• The second form specifies both the column
names and the values to be inserted:
• INSERT INTO table_name (column1,
column2, column3,...)
VALUES (value1, value2, value3,...)

• SQL INSERT INTO Example
• We have the following "Persons" table:
:
Now we want to insert a new row in the "Persons" table.
We use the following SQL statement
INSERT INTO Persons
VALUES (4,'Nilsen', 'Johan', 'Bakken 2', 'Stavanger')
4 Nilsen Johan Bakken 2 Stavanger

• Insert Data Only in Specified Columns
• It is also possible to only add data in specific columns.
• The following SQL statement will add a new row, but
only add data in the "P_Id", "LastName" and the
"FirstName" columns:
• INSERT INTO Persons (P_Id, LastName, FirstName)
VALUES (5, 'Tjessem', 'Jakob')
• The "Persons" table will now look like this:
5 Tjessem Jakob

• The SQL SELECT Statement
• The SELECT statement is used to select data from a
database. The result is stored in a result table, called
the result-set.
• SQL SELECT Syntax
• SELECT column_name(s)
FROM table_name
• SELECT * FROM table_name
And
• ‘*’ Also called as Global Extraction Opearator
• Note: SQL is not case sensitive. SELECT is the same
as select.
• An SQL SELECT Example

• SQL CHECK Constraint on CREATE TABLE
• The following SQL creates a CHECK constraint
on the "P_Id" column when the "Persons" table
is created. The CHECK constraint specifies that
the column "P_Id" must only include integers
greater than 0.
(
P_Id int NOT NULL CHECK (P_Id>0),
City varchar(25)
)

• To allow naming of a CHECK constraint,
and for defining a CHECK constraint on
multiple columns, use the following SQL
syntax:
CREATE TABLE Persons
(
P_Id int NOT NULL,
City varchar(255),
CONSTRAINT chk_Person CHECK (P_Id>0 AND
City='Sandnes')
)

• SQL CHECK Constraint on ALTER
TABLE
• To create a CHECK constraint on the "P_Id"
column when the table is already created, use
the following SQL:
ADD CHECK (P_Id>0)
• To allow naming of a CHECK constraint, and for
defining a CHECK constraint on multiple
columns, use the following SQL syntax:
ADD CONSTRAINT chk_Person CHECK
(P_Id>0 AND City='Sandnes')

• To DROP a CHECK Constraint
• To drop a CHECK constraint, use the
following SQL:
DROP CONSTRAINT chk_Person;

• The DROP TABLE Statement
• The DROP TABLE statement is used to
delete a table.
DROP TABLE table_name

• SQL SELECT Syntax
FROM table_name
• SELECT * FROM table_name
• And
• ‘*’ Also called as Global Extraction
Opearator

1 Hansen Ola
Timoteivn
10
Sandnes

• SELECT LastName,FirstName FROM
Persons
• The result-set will look like this:
By:-Gourav Kottawar
LastName FirstName
Hansen Ola
Svendson Tove
Pettersen Kari
55

• The SQL SELECT DISTINCT Statement
• In a table, some of the columns may
contain duplicate values. This is not a
problem, however, sometimes you will
want to list only the different (distinct)
values in a table.
• The DISTINCT keyword can be used to
return only distinct (different) values.

• SELECT DISTINCT column_name(s)
FROM table_name
• SELECT DISTINCT Example
SELECT DISTINCT City FROM Persons;
• City
• Sandnes
• Stavanger

• CLAUSES IN SQL The WHERE Clause
FROM table_name
WHERE column_name operator value

• SELECT * FROM Persons
WHERE City='Sandnes'
By:-Gourav Kottawar
1 Hansen Ola
Timoteivn
10
Sandnes
59

• This is correct:
SELECT * FROM Persons WHERE
FirstName='Tove‘ ;
This is wrong:
FirstName=Tove

Year=1965
This is wrong:
Year='1965'

• Operators Allowed in the WHERE Clause
• With the WHERE clause, the following operators can
be used:
By:-Gourav Kottawar
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 If you know the exact value you want to
return for at least one of the columns
62

• Now we want to select only the persons
with the first name equal to "Tove" AND
the last name equal to "Svendson":
• We use the following SELECT statement:
WHERE FirstName='Tove'
AND LastName='Svendson‘ ;

By:-Gourav Kottawar
64

• Now we want to select only the persons
with the first name equal to "Tove" OR the
first name equal to "Ola":We use the
following SELECT statement:
OR FirstName='Ola‘ ;

• SELECT * FROM Persons WHERE
LastName='Svendson'
AND (FirstName='Tove' OR
FirstName='Ola');
By:-Gourav Kottawar
P_Id LastName FirstNameAddress City
2 Svendson Tove Borgvn 23Sandnes
67

• SQL IN Operator
• The IN Operator
• The IN operator allows you to specify
multiple values in a WHERE clause.
• SQL IN Syntax:
FROM table_name
WHERE column_name IN
(value1,value2,...)

• IN Operator Example
WHERE LastName IN
('Hansen','Pettersen')

_Id LastName FirstName Address City

• SQL BETWEEN Operator
• The BETWEEN operator is used in a
WHERE clause to select a range of data
between two values.
• The BETWEEN Operator
• The BETWEEN operator selects range of
data between two values. The values can
be numbers, text, or dates.

• SQL BETWEEN Syntax:SELECT
column_name(s)
FROM table_name
WHERE column_name
BETWEEN value1 AND value2

LIKE Operator
• Using the % Wildcard
• 1.Now we want to select the persons living in a city that
starts with "sa" from the "Persons" table.
WHERE City LIKE 'sa%'
P_Id LastName
FirstNam
e
Address City

• 2. Next, we want to select the persons
living in a city that contains the pattern
"nes" from the "Persons" table.
WHERE City LIKE '%nes%'
• The result-set will look like this

• 3.Now we want to select the persons with
a first name that starts with any character,
followed by "la" from the "Persons" table.
WHERE FirstName LIKE '_la'

• 4.Next, we want to select the persons with a
last name that starts with "S", followed by
any character, followed by "end", followed
by any character, followed by "on" from the
"Persons" table.
WHERE LastName LIKE 'S_end_on'
_Id LastName FirstName Address City

• Using the [charlist] Wildcard
• 5.Now we want to select the persons with
a last name that starts with "b" or "s" or "p"
from the "Persons" table.
WHERE LastName LIKE '[bsp]%'

• 5.Next, we want to select the persons with
a last name that do not start with "b" or "s"
or "p" from the "Persons" table.
WHERE LastName LIKE '[!bsp]%'

• The UPDATE Statement
• The UPDATE statement is used to update
existing records in a table.
• SQL UPDATE Syntax
• UPDATE table_name
SET column1=value, column2=value2,...
WHERE some_column=some_value

• Note: Notice the WHERE clause in the UPDATE syntax.
The WHERE clause specifies which record or records
that should be updated. If you omit the WHERE clause,
all records will be updated!
• SQL UPDATE Example :The "Persons" table
5 Tjessem Jakob

• Now we want to update the person "Tjessem,
Jakob" in the "Persons" table.
• We use the following SQL statement:
• UPDATE Persons
SET Address='Nissestien 67', City='Sandnes'
WHERE LastName='Tjessem' AND FirstName='Jakob‘;
5 Tjessem Jakob Nissestien 67 Sandnes

• The SQL SELECT DISTINCT Statement
• In a table, some of the columns may contain
duplicate values. This is not a problem,
however, sometimes you will want to list only
the different (distinct) values in a table.
• The DISTINCT keyword can be used to
return only distinct (different) values.
• SQL SELECT DISTINCT Syntax
• SELECT DISTINCT column_name(s)
FROM table_name
• SELECT DISTINCT Example

3 Pettersen Kari Storgt 20
Stavange
r

• CLAUSES IN SQL
• The WHERE Clause
• The WHERE clause is used to extract only
those records that fulfill a specified criterion.
– SQL WHERE Syntax
FROM table_name

• WHERE Clause Example
SELECT * FROM Persons
WHERE City='Sandnes'
Now we want to select only the persons living
in the city "Sandnes" from the table above.
We use the following SELECT statement:
The result-set will look like this:

Quotes Around Text Fields
SQL uses single quotes around text values (most database
systems will also accept double quotes).
Although, numeric values should not be enclosed in
quotes.

SELECT * FROM Persons WHERE FirstName='Tove'
This is wrong:
SELECT * FROM Persons WHERE FirstName=Tove
• For numeric values:
SELECT * FROM Persons WHERE Year=1965
This is wrong:
SELECT * FROM Persons WHERE Year='1965'

• Operators Allowed in the WHERE
Clause
• With the WHERE clause, the following
operators can be used:
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
If you know the exact value you want to
return for at least one of the columns

• The AND operator displays a record if both the
first condition and the second condition is true.
• The OR operator displays a record if either the
first condition or the second condition is true.
• AND Operator Example

• Now we want to select only the persons with the
first name equal to "Tove" AND the last name
equal to "Svendson":
AND LastName='Svendson‘
2 Svendson Tove
Borgvn
23
Sandnes

• OR Operator Example
• Now we want to select only the persons with the
first name equal to "Tove" OR the first name
equal to "Ola":We use the following SELECT
statement:
OR FirstName='Ola'

Combining AND & OR
You can also combine AND and OR (use parenthesis to form
complex expressions).
Now we want to select only the persons with the last name
equal to "Svendson" AND the first name equal to "Tove" OR to
"Ola":
We use the following SELECT statement:
LastName='Svendson'
AND (FirstName='Tove' OR FirstName='Ola')

• SQL IN Operator
• The IN Operator
• The IN operator allows you to specify multiple values in a
WHERE clause.
• SQL IN Syntax:
FROM table_name
WHERE column_name IN (value1,value2,...)

• IN Operator Example
• Now we want to select the persons with a last name
equal to "Hansen" or "Pettersen" from the table
above.
WHERE LastName IN ('Hansen','Pettersen')

• SQL BETWEEN Operator
• The BETWEEN operator is used in a WHERE clause to
select a range of data between two values.
• The BETWEEN Operator
• The BETWEEN operator selects range of data between
two values. The values can be numbers, text, or dates.
• SQL BETWEEN Syntax:SELECT column_name(s)
FROM table_name
WHERE column_name
BETWEEN value1 AND value2
•
•
• By:-Gourav Kottawar 95

WHERE LastName
BETWEEN 'Hansen' AND 'Pettersen'
1 Hansen Ola
Timoteivn
10
Sandnes
To display the persons outside the range in the
previous example, use NOT BETWEEN:
SELECT * FROM Persons
WHERE LastName
NOT BETWEEN 'Hansen' AND 'Pettersen'
The result-set will look like this:

ORDER BY clause
• So far, we have seen how to get data out
of a table using SELECT and WHERE
commands. Often, however, we need to
list the output in a particular order. This
could be in ascending order, in
descending order, or could be based on
either numerical value or text value. In
such cases, we can use the ORDER BY
keyword to achieve our goal.

• The syntax for an ORDER BY statement is
as follows:
• SELECT "column_name"
FROM "table_name"
[WHERE "condition"]
ORDER BY "column_name" [ASC,
DESC]

• The [] means that the WHERE statement
is optional. However, if a WHERE clause
exists, it comes before the ORDER BY
clause. ASC means that the results will be
shown in ascending order, and DESC
means that the results will be shown in
descending order. If neither is specified,
the default is ASC.

• For example, we may wish to list the
contents of Table Store_Information by
dollar amount, in descending order:
By:-Gourav Kottawar
store_name Sales Date
Los Angeles $1500 Jan-05-1999
Boston $700 Jan-08-1999
San
Francisco
$300 Jan-08-1999
San Diego $250 Jan-07-1999
100

• The GROUP BY Statement
• The GROUP BY statement is used in
conjunction with the aggregate functions to
group the result-set by one or more
columns.
• SQL GROUP BY Syntax:
• SELECT column_name,
aggregate_function(column_name)
FROM table_name
GROUP BY column_name

O_Id OrderDate OrderPrice Customer
1 2008/11/12 1000 Hansen
2 2008/10/23 1600 Nilsen
3 2008/09/02 700 Hansen
4 2008/09/03 300 Hansen
5 2008/08/30 2000 Jensen
6 2008/10/04 100 Nilsen

• Now we want to find the total sum (total order) of each
customer.
• We will have to use the GROUP BY statement to group
the customers.
• We use the following SQL statement:
• SELECT Customer, SUM(OrderPrice)
FROM Orders
GROUP BY Customer
By:-Gourav Kottawar
Customer SUM(OrderPrice)
Hansen 2000
Nilsen 1700
Jensen 2000
103

• We can also use the GROUP BY
statement on more than one column, like
this:
• SELECT
Customer,OrderDate,SUM(OrderPrice)
FROM Orders
GROUP BY Customer,OrderDate

• Date functions in SQL
•
• 1. SYSDATE() Sysdate to diplay system
date.
•
• SQL> select sysdate from dual;
•
• SYSDATE
• ---------
• 23-NOV-10
• By:-Gourav Kottawar 105

• 2. LAST_DAY: Last_day to display last
day of the current/mentioned date.
•
• SQL> select last_day(sysdate) from
dual;
•
• LAST_DAY
• ---------
• 30-NOV-10

• SQL> select last_day('06-nov-2010') from dual;
• LAST_DAY
• ---------
• 30-NOV-10
• 3. NEXT_DAY : to display next day of the mentioned
date,that is if today if 6th dec and today id Monday then
when will next day
• SQL> Select next_day('06-dec-2010','Monday') from
• dual;
•

4. MONTHS_BETWEEN : Calculates the months between
the two dates.
• select months_between('02-feb-2010','03-Dec-2009')
from dual;
• MONTHS_BETWEEN('02-FEB-2010','03-DEC-2009')
-------------------------------------------
1.9677419
5. ADD_MONTHS adds month to the current date.
•
• SQL> select add_months(sysdate,4) from dual;
•
• ADD_MONTH
---------
• 23-MAR-11 By:-Gourav Kottawar 108

• SQL Aggregate Functions
• SQL aggregate functions return a single
value, calculated from values in a column.
• Useful aggregate functions:
• AVG() - Returns the average value
• COUNT() - Returns the number of rows
• FIRST() - Returns the first value
• LAST() - Returns the last value
• MAX() - Returns the largest value
• MIN() - Returns the smallest value
• SUM() - Returns the sum

• SQL COUNT(*) Example
• SELECT COUNT(*) FROM Orders;

• MANIPULATION in DATES in SQL
1. TOCHAR:
• To retrieve date in a format other than default format.
• select to_char (sysdate,'DD-MM-YY') from dual;
TO_CHAR(
--------
23-11-10
2.TO_DATE
•
• select to_date('06/07/2010','DD/MON/YY') from dual;
• TO_DATE('
• ---------
06/JUL/10

• The MAX() Function
• The MAX() function returns the largest
value of the selected column.
• SQL MAX() Syntax:SELECT
MAX(column_name) FROM table_name
• SELECT MAX(OrderPrice) AS
LargestOrderPrice FROM Orders

• SQL MIN() Function
• The MIN() function returns the smallest
value of the selected column.
• SQL MIN() Syntax:SELECT
MIN(column_name) FROM table_name
• SELECT MIN(OrderPrice) AS
SmallestOrderPrice FROM Orders

• The SUM() Function
• The SUM() function returns the total sum
of a numeric column.
• SQL SUM() Syntax: SELECT
SUM(column_name) FROM table_name
• SELECT SUM(OrderPrice) AS
OrderTotal FROM Orders

SQL STRING FUNCTION
1.SUBSTR
• Table Geography region_name
store_name East Boston East New York
West Los Angeles West San Diego
• Example 1:
• SELECT SUBSTR(store_name, 3)
FROM Geography
WHERE store_name = 'Los Angeles';

• Result:
• 's Angeles'
• Example 2:
• SELECT SUBSTR(store_name,2,4)
FROM Geography
WHERE store_name = 'San Diego';
• Result:
• 'an D'

• 2.LTRIM(str): Removes all white spaces
from the beginning of the string.
• 3.RTRIM(str): Removes all white spaces
at the end of the string.
• Example 1:
• SELECT TRIM(' Sample ') from
tablename;
• Result:
• 'Sample'

• Example 2:
• SELECT LTRIM(' Sample ');
• Result:
• 'Sample '
• Example 3:
• SELECT RTRIM(' Sample ');
• Result:
• ' Sample'

• 4. Length(str): Find the length of the
string str.
By:-Gourav Kottawar
region_name store_name
East Boston
East New York
West Los Angeles
West San Diego
119

• Example 1:
• SELECT Length(store_name)
FROM Geography
WHERE store_name = 'Los Angeles';
• Result:
• 11

• Example 2:
• SELECT region_name,
Length(region_name)
FROM Geography;
• Result:
By:-Gourav Kottawar
region_name
Length(regio
n_name)
East 4
East 4
West 4
West 4
121

• 5.Replace(str1, str2, str3): In str1, find
where str2 occurs, and replace it with str3.
• SELECT REPLACE(region_name, 'ast',
'astern')
FROM Geography;
By:-Gourav Kottawar
region_name
Eastern
Eastern
West
West
122

• 6. CONCAT
• CONCAT(str1, str2, str3, ...):
Concatenate str1, str2, str3, and any other
strings together. Please note the Oracle
CONCAT() function only allows two
arguments -- only two strings can be put
together at a time using this function.
However, it is possible to concatenate
more than two strings at a time in Oracle
using '||'.

• SELECT
CONCAT(region_name,store_name)
FROM Geography
WHERE store_name = 'Boston';
• Result:
'EastBoston'
• SELECT region_name || ' ' ||
store_name FROM Geography
WHERE store_name = 'Boston';
• Result:
'East Boston' By:-Gourav Kottawar 124

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