Database Programming using SQL

Introduction to DatabaseLab: Introduction to Oracle and SQL

(CSE 3151)

Lab - 0

Ajit K Nayak, Ph.D.

Siksha ‘O’ Anusandhan UniversityAug 2016

Ajit K Nayak1.2Introduction to databases

Relational Model

The relational model uses a set of tables/

relations to represent data and the relationship

among those data for a specific enterprise.

Each table is arranged in a two dimensional

matrix, i.e. columns and rows.

Each column has a unique name called

fields/attributes of the relation.

Each row is a record of the relation type.


Example: Table / relation


SQL

Edgar F. Codd, designed a set of rules

(Codds rule) for ideal relational database

management system.

Structured Query Language (SQL) was one of

the first commercial languages that is used

widely as a database language.

SQL adheres to some of the Codd’s rules.

SQL became a standard of ANSI in 1986, and

of the International Organization for

Standardization (ISO) in 1987.

Both the standards are identical


Oracle

Oracle Database is an object-relational

database management system developed

by Oracle Corporation.

It uses SQL as the language and complies to

the ANSI/ISO standards

SQL consists of

a data definition language(DDL),

a data manipulation language(DML),

a and Data Control Language(DCL).

The names are according to their function.


DDL

A data definition language or data

description language (DDL) provides syntax

for defining data structures, especially

database schemas.

Statements are

CREATE : to create tables etc.

DROP: to delete table

ALTER: to change an object (field, type, etc)

RENAME: to rename a table


DML

A data manipulation language (DML)

provides a family of syntax elements used to

operate on the data in table.

Statements are

SELECT : to retrieve data from table.

INSERT: to insert records into the table

UPDATE: to change data inside table

DELETE: to delete rows/records from a table


DCL

A data control language (DCL) is used to

control access to data stored in a database

(Authorization).

Statements are

GRANT : to allow specified users to perform

specified tasks.

REVOKE: to cancel previously granted or denied

permissions.


Datatypes - MinimalData type Description

CHARACTER(n) Character string. Fixed-length n

VARCHAR(n) Character string. Variable length. Maximum

length n

BOOLEAN Stores TRUE or FALSE values

INTEGER Integer numerical (no decimal).

NUMERIC(p,s) precision p, scale s. Example: numeric(5,2) is

a number that has 3 digits before the decimal

and 2 digits after the decimal

DATE Stores year, month, and day values

TIME Stores hour, minute, and second values


Experiment TimeLet’s create, insert and retrieve


Create Table - I

SQL is case insensitive. However, try to follow

one case only.

To create a table we need atleast:

The table name (r)

the names of the columns (A1, A2, . . .)

Datatype of columns in order (D1, D2, D3, . . .)

Syntax

create table r (A1 D1, A2 D2, ..., An Dn);


Create Table - II

Let’s create the table as shown.

create table instructor (

ID char(5),

name varchar(20),

dept_name varchar(20),

salary numeric(8,2));

instructor


Insert Records - I

To insert into a table we need:

The table name (r)

value of the columns in order (V1, V2, V3, . . .)

Syntax

insert into r values(V1, V2, ..., Vn);


Insert records - II

Let’s insert records in the table instructor.

insert into instructor values (‘10101’, ’Srinivasan’, ’Comp.Sci’, 65000);

insert into instructor values (‘12121’, ’Wu’, ’Finance’, 90000);

. . .

instructor


Retrieve data – The SELECT statement

The select statement lists the attribute values in

the result of a query

Syntax

select column(s)

from table(s)

where condition(s) (optional)

NOTE: SQL names are case insensitive (i.e., you

may use upper- or lower-case letters.)

E.g., Name ≡ NAME ≡ name


The SELECT statement -II

from and where are two clauses used with select

statements. The where clause is optional

Example

select name

from instructor

Output : Lists all the names inserted into table

instructor.Srinivasan

Wu

Mozart

Einstein

. . .


The SELECT statement -III

Example

select name

from instructor

where salary < 65000

OutputLists all the names in table instructor

having salary less than 65000.Mozart

El Said

. . .


Assignment - I


End of Lab 1

Thank You

Introduction to DatabaseLab: Basic Operations in SQL

(CSE 3151)

Lab - 2

Ajit K Nayak, Ph.D.



Review

SQL is a standard for database (relational)

programming having following components

DDL

To define the relations

DML

To access or manipulate data inside relation

DCL

To provide access permissions

TCL (Transaction Control Language)

Transaction control (COMMIT, ROLLBACK,

SAVEPOINT)


Transaction Control - I

Transaction is a unit of a program execution

that accesses and possibly modifies various

data objects (reading, writing)

Some of the transaction make permanent

changes in the database but some are not.

COMMIT is used to save changes permanently

in a database manually.

DDL commands uses implicit COMMIT (auto

commit),

But DML needs explicit COMMIT. (to be issued

manually)


Transaction Control - II

Until you commit a transaction (DML):

You can see any changes you have made during

the transaction by querying the modified tables.

(local change)

But other users cannot see the changes.

After you commit the transaction, the changes are

visible to other users' statements that execute after

the commit. (global change)

You can roll back (undo) any changes made

during the transaction with the ROLLBACK

statement.

So, before leaving the lab issue: COMMIT;


UPDATE

Used to change/modify one or more records.

Conditional Update

UPDATE instructor

SET name = „Uthhapa‟

WHERE name = „Wu‟;

Update all rows

UPDATE instructor

SET name = salary = salary+100;


DELETE

To delete one or more rows

Conditional delete

DELETE FROM instructor

WHERE name = „Wu‟;

Delete all rows

DELETE FROM instructor;


The Select Statement - I The select statement may be used in following

situations

Projection: to choose one or

more columns in a table.

Selection: to choose one or

more columns in a table.


The Select Statement - II

Joining: to bring together data that is

stored in different tables by creating a

link between them.


Operations

Arithmetic Operations

+, -, *, /

Column Alias

Concatenation Operator (II)

DISTINCT operator

Comparison Operations (<, >, >=,<=, BETWEEN,

IN, LIKE, NULL)

Logical Operators (AND, OR, NOT)


Examples - I

Arithmetic

1) SELECT name, salary, salary * 0.3

FROM instructor;

Alias

2) SELECT name, salary, salary *0.3 AS diff

FROM instructor;

Concatenation (||)

3) SELECT name || „ belongs to ‟||

dept_name “Employee Dept”

FROM instructor;


Examples - II

SELECT dept_name from instructor;

Displays all the departments with duplcates

DISTINCT : Eliminates duplicate rows

4) SELECT DISTINCT dept_name

FROM instructor;

BETWEEN (Between two values inclusive)

5) SELECT name, salary

FROM instructor

WHERE salary BETWEEN 40000 AND 60000;


Examples - III

IN (set): to chose values from a list

6) SELECT name, dept_name

FROM instructor

WHERE dept_name IN (Comp.Sci, Physics);

LIKE: wildcard search

% : denotes zero or more characters

_ : denotes one character

7) SELECT name

FROM employees

WHERE name LIKE ‟E%‟;


Examples - IV

AND

8) SELECT id, name

FROM instructor

WHERE salary >= 50000

AND dept_name LIKE ‟Comp%‟;

NOT

9) SELECT name, id

FROM employees

WHERE dept_name

NOT IN (‟History‟, ‟Biology‟);


Group Functions

group functions operate on sets of rows to give

one result per group.

These sets may be the whole table or the table

split into groups.

AVG

COUNT

MAX

MIN

STDDEV

SUM

VARIANCE


Group Functions Example

SELECT AVG(salary), MAX(salary),

MIN(salary), SUM(salary)

FROM instructor;


Group Functions Example

1) SELECT AVG(salary), MAX(salary),

MIN(salary), SUM(salary)

FROM instructor;

Who is getting highest salary?

2) SELECT name, Dept, salary

FROM instructor

WHERE salary = (

SELECT MAX(salary)

FROM instructor);


Maintaining Lab Records

Use plain A4 sheet

Design a cover page stating

Reg. No, Name, Branch, Section, session, college

name, university name

Design a content page containing assignment

number, date, page no of solution

Write the question, query, output of the query

Submit for verification in next lab.


Task

Execute all the queries discussed

Solve Assignment 2


End of Lab 2

Thank You

Introduction to DatabaseLab: Functions in SQL

(CSE 3151)

Lab - 3

Ajit K Nayak, Ph.D.



Dual Table

If you want to have some task without using a

table…

Today’s date

Solve an arithmetic expression (3+4)

. . .

But the select command needs a table…

Oracle provides a 1x1 dummy table for these purpose

SELECT sysdate from DUAL;

SELECT 3+4 from DUAL;

SELECT * from DUAL;

SELECT 1 from DUAL;


Single row functions: character To manipulate character data

LOWER, UPPER, INITCAP, CONCAT, SUBSTR, INSTR, LENGTH,

LPAD, RPAD, TRIM, REPLACE

Examples

LOWER(’SQL Course’) output: sql course

UPPER(’SQL Course’) output: SQL COURSE

INITCAP(’SQL Course’) output: Sql Course

CONCAT(’Hello’, ’World’) output: HelloWorld

SUBSTR(’HelloWorld’,1,5) output: Hello

LENGTH(’HelloWorld’) output: 10

INSTR(’HelloWorld’, ’W’) output: 6

LPAD(salary,10,’*’) output: *****24000

RPAD(salary, 10, ’*’) output: 24000*****

TRIM(’H’ FROM ’HelloWorld’) output: elloWorld


Single row functions: Numeric

To Manipulate Numeric data

ROUND, TRUNC, MOD, ABS, ACOS, ASIN, ATAN,

ATAN2, BITAND, CEIL, COS, COSH, EXP, FLOOR, LN,

LOG , POWER, SIGN, SIN, SINH, SQRT, TAN,

TANH, TRUNC

Examples

ROUND(45.926, 2) output: ?

TRUNC(45.926, 2) output: ?

MOD(1600, 300) output: ?

ABS(-87) output: ?

CIEL(3.456) output: ?

COS(60) output: ?

POWER(2,3) output: ?


End of Lab 3

Thank You

Introduction to DatabaseLab: Sorting and DDL

(CSE 3151)

Lab - 4

Ajit K Nayak, Ph.D.Siksha ‘O’ Anusandhan University

Aug 2016


Sorting rows

The clause ORDER BY is used to display sorted

outputs.

It has to be used as the last clause of any

select statement.

SELECT name, salary

FROM instructor

ORDER BY salary ASC;

ASC is default case.

DESC is used for descending order It is also possible to sort according to multiple columns


Grouping rows

The clause can’t be used to select individual

rows. Used with group functions.

The result is sorted ASC by default

Order by clause may e used with this clause.

SELECT dept_name, AVG(salary)

FROM instructor

GROUP BY dept_name;

Do not used WHERE, HAVING clause may be

used to restrict resultant groups.

HAVING AVG(salary) > 60000;


DDL Commands - I

ALTER TABLE statement can be used to:ADD a new column

MODIFY an existing column

Define a default value for the new column

DROP a column


ALTER TABLE - I

ADD a column to an existing table

ALTER TABLE instructor

ADD (doj date);Adds a new column doj at the end.

MODIFY a column datatype


MODIFY (name varchar2(30));Can modify type, size, default values of cols.


ALTER TABLE - II

MODIFY a default value


MODIFY (salary numeric(8,2) default 1000);

DROP a column


DROP COLUMN doj;

MARK UNUSED a columnALTER TABLE instructor

SET UNUSED (doj);

At a later time


DROP UNUSED COLUMNS;


DDL - II

Renaming objects

Rename a table

RENAME instructor TO faculty;

Rename a table columnALTER TABLE instructor

RENAME COLUMN dept_name TO department;


DDL - III

Truncate statement removes all the rows

from a table.

TRUNCATE TABLE instructor;

Drop statement removes rows and table

structureDROP TABLE instructor;


End of Lab 4

Thank You

Introduction to DatabaseLab: Data Constraints

(CSE 3151)

Lab - 5

Ajit K Nayak, Ph.D.


Ajit K Nayak5.2Introduction to databases LAB

Constraints in Oracle

Constraints enforce rules into the tables that

Can enforce rules on data when a row is inserted,

updated, or deleted. That is the constraints must be

satisfied for the operation to succeed.

Prevent the deletion of a table if there are

dependencies from other table

Constraints can be defined in either column

level or table level

Either a constraint can be defined while creating a

table (CREATE TABLE), Or it can be added at a later

time to an existing table (ALTER TABLE)


Constraint Types

Constraints

I/O Constraints

Business rule Constraints

Primary Key Constraint

Foreign Key Constraint

Not NULL Constraint

Unique Constraint

CHECK Constraint


Constraints - I

Constraints Description

NOT NULL Specifies that the column can’t contain a null

value

UNIQUE Specifies a column or combination of columns

whose values must be unique for all rows in the

table but allows some values to be null.

PRIMARY KEY Uniquely identifies each row of the table

(unique + not null)

FOREIGN KEY Requires values in one table to match values in

another table.

CHECK Requires a value in the database to comply

with a specified condition.


Constraint Levels

Column level Constraints

Applied to the current column called inline

specification.

i.e. local to a specific column

Can’t be applied if data constraints span across

multiple columns in a table

Table level Constraints

It is applied when data constraints span across

multiple columns in a table (out-of-line specification)

Defined after defining all table columns

Stored as a part of global table definition


NULL Value

NULL value

Used for a column when we do not have a value

for that column

It can be used for columns of any data type

When no value is supplied for a column, Oracle

assumes NULL value for that column (default)

It is different from blank or zero values

If the column has already a NULL value in it, then

Oracle ignores the UNIQUE, FOREIGN, and CHECK

constraints

NOT NULL constraints must be declared inline. All

other constraints can be declared either inline or

out of line.


NOT NULL

If the table is not yet created

CREATE TABLE customers(

id INT NOT NULL,

name VARCHAR2(20) NOT NULL,

address VARCHAR2(25) ,

salary NUMERIC(18, 2) );

If the table is existing

ALTER TABLE CUSTOMERS

MODIFY salary NUMERIC(18, 2) NOT NULL;


UNIQUE - I in-line


id INT NOT NULL,

name VARCHAR2(20) UNIQUE,

address VARCHAR2(25) ,

salary NUMERIC(18, 2) );

Out-of-line


. . .

UNIQUE (name, address) );

OR

CONSTRAINT cust_add UNIQUE(name, address)

A Name may be assigned

to the constraint


UNIQUE - II

In Existing table

ALTER TABLE customers

ADD UNIQUE (address);

In Existing table (with constraint name)


ADD CONSTRAINT cust_add UNIQUE(name, address);

Drop a constraint


DROP CONSTRAINT cust_add;


Primary Key CREATE TABLE

id INT PRIMARY KEY,

. . .

Or

PRIMARY KEY (id, name)

Or

CONSTRAINT cust_id PRIMARY KEY (id, name)

ALTER TABLE

ADD PRIMARY KEY (id, name)

DROP KEY

DROP CONSTRAINT cust_id


Foreign Key - I A FOREIGN KEY in one table points to a PRIMARY KEY in

another table.

cid LastName FirstName Address City

1 Hansen Ola Timoteivn 10 Sandnes

2 Svendson Tove Borgvn 23 Sandnes

3 Pettersen Kari Storgt 20 Stavanger

oid OrderNo cid

1 77895 3

2 44678 3

3 22456 2

4 24562 1

“cid" column in the orders table points

to the “cid" column in the customer

table.

The “cid" column is the PRIMARY KEY

in the customer table and is a

FOREIGN KEY in the order table.


Foreign Key – Create table

Column level

CREATE TABLE orders(

oid int PRIMARY KEY,

OrderNo int NOT NULL,

cid int REFERENCES customer(cid));

Table level




cid int,

CONSTRAINT fk_order FOREIGN KEY (cid)

REFERENCES customer(cid));


Foreign Key – Alter table

Column level

ALTER TABLE orders

ADD FOREIGN KEY (cid)

REFERENCES customer(cid);

Table level

ALTER TABLE orders

ADD CONSTRAINT fk_order

FOREIGN KEY (cid)

REFERENCES customer(cid);

DROP

ALTER TABLE orders

DROP CONSTRAINT fk_order;


After Referencing

Extract information from two tables with

referential integritySELECT lastname, address, city, orderNo

FROM customer, orders

WHERE customer.cid = order.cid;


Restrictions with referential integrity

Deletion restriction

Rows containing Referenced key values in the

parent table can’t be deleted that have

dependent rows in the child table.

Method 1 (Manual/ not advised)

Delete the row from child table

Then delete from parent table

Method 2 (Automated)

Use either ON DELETE CASCADE

or ON DELETE SET NULL clauses

Then oracle will automatically delete corresponding

rows in child table along with rows of parent table


Restrictions with referential integrity

Insertion restriction

A row can’t be inserted into the child table if

referenced key values are not available in the

parent table.

Method

Insert into the parent table

Then insert into child table


Deleting rows with referential integrity

Example:




cid int,

CONSTRAINT fk_order FOREIGN KEY (cid)

REFERENCES customer(cid)

ON DELETE CASCADE

);


CHECK constraint

Applying business rule (mob# and email id)

CREATE TABLE customer (

. . .

mobNo char(10),

eMail varchar2(50));

ALTER TABLE customer

ADD CONSTRAINT ch_mob

CHECK (mobNo LIKE

'[0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9]');

ALTER TABLE customer

ADD CONSTRAINT ch_mail

CHECK (eMail Like '_%@_%._%');


End of Lab 5

Thank You

Introduction to DatabaseLab: Subquery

(CSE 3151)

Lab - 6

Ajit K Nayak, Ph.D.



Subquery? Some times you may need two queries to

solve a single problem.

Ex: Who has a salary greater than Abel’s?

Subquery: What is Abel’s Salary?

Mainquery: Which employees salaries greater than

Abel’s salary.

Syntax:SELECT <columns>

FROM <table>

WHERE <expression>

(SELECT <columns>

FROM <table>

WHERE <expression>);

Subquery/

Innerquery

Mainquery/

Outerquery


Example Ex: Find the employee names getting more

salary than Abel’s.

SELECT name

FROM employee

WHERE salary >

(SELECT salary

FROM employees

WHERE name = “Abel”);


Subquery Types Single-row subqueries: Queries that return only

one row from the inner SELECT statement

Use single-row comparison operators

=, >, >=, <, <=, <>

Multiple-row subqueries: Queries that return

more than one row from the inner SELECT

statement

Use multiple-row comparison operators

IN, ANY, ALL


Single-row subqueries - I Display the employees name and job ID

whose job ID is the same as that of employee

141.

SELECT name, job_id

FROM employees

WHERE job_id =

(SELECT job_id

FROM employees

WHERE employee_id = 141);


Single-row subqueries - II Display the employees name and job_id whose job ID

is the same as that of employee 141 and salary same

as that of employee 143.

SELECT name, job_id

FROM employees

WHERE job_id =

(SELECT job_id

FROM employees

WHERE employee_id = 141)

AND salary >

(SELECT salary

FROM employees

WHERE employee_id = 143);


Single-row subqueries - III Display the employees name, job_id, salary, who are

getting min salary.

SELECT name, job_id, salary

FROM employees

WHERE salary =

(SELECT MIN(salary)

FROM employees);

List the departments getting min salary greater than the dept 50

SELECT dept_id, MIN(salary)

FROM employees

GROUP BY dept_id

HAVING MIN(salary) >

(SELECT MIN(salary)

FROM employees

WHERE dept_id = 50);


Multiple-row subqueries - I List the employees of different department getting

minimum salary.

SELECT name, salary, dept_id

FROM employees

WHERE salary IN

(SELECT MIN(salary)

FROM employees

GROUP BY dept_id);


Multiple-row subqueries - II Find employees info of employees getting salary less

than any IT programmers

SELECT emp_id, name, job_id, salary

FROM employees

WHERE salary < ANY

(SELECT salary

FROM employees

WHERE job_id = ’IT_PROG’)

AND job_id <> ’IT_PROG’;


Multiple-row subqueries - III Find employees info of employees salary less than all IT

programmers

SELECT employee_id, last_name, job_id, salary

FROM employees

WHERE salary < ALL

(SELECT salary

FROM employees

WHERE job_id = ’IT_PROG’)

AND job_id <> ’IT_PROG’;


Problem with Subquery

A common problem with subqueries is

no rows being returned by the inner

query.


End of Lab 6

Thank You

Introduction to DatabaseLab: Joining Tables

(CSE 3151)

Lab - 7

Ajit K Nayak, Ph.D.Siksha ‘O’ Anusandhan University

Aug 2016


Joining Tables

to obtain data from more than one table using

equality and non-equality joins

Join a table to itself by using a self join


Obtaining data from multiple tables


Cartesian Products

A Cartesian product is formed when: A join condition is omitted

A join condition is invalid

All rows in the first table are joined to all rows in the

second table

A Cartesian product tends to generate a large

number of rows, and the result is rarely useful.

To avoid a Cartesian product, always include

a valid join condition in a WHERE clause.


Cartesian Products: Example SELECT last_name, department_name dept_name

FROM employees, departments;


Generating a Cartesian Product


Joining Tables: Equijoins SELECT table1.column, table2.column

FROM table1, table2

WHERE table1.column1 = table2.column2;

SELECT employees.employee_id, employees.last_name,

employees.department_id, departments.department_id,

departments.location_id

FROM employees, departments

WHERE employees.department_id =

departments.department_id;


Additional Search Conditions SELECT last_name, employees.department_id,

department_name

FROM employees, departments

WHERE employees.department_id =

departments.department_id

AND last_name = ’Matos’;


Using Table alias SELECT e.employee_id, e.last_name, e.department_id,

d.department_id, d.location_id

FROM employees e , departments d

WHERE e.department_id = d.department_id;


Joining More than Two Tables SELECT e.last_name, d.department_name, l.city

FROM employees e, departments d, locations l

WHERE e.department_id = d.department_id

AND d.location_id = l.location_id;


Joining more than two tables


Self Joins Sometimes you need to join a table to itself.

Ex: To find the name of each employee’s manager,

Need to join the EMPLOYEES table to itself, or

perform a self join.

SELECT worker.last_name || ’ works for ’||

manager.last_name

FROM employees worker, employees manager

WHERE worker.manager_id = manager.employee_id


Self Joins


End of Lab 7

Thank You

Date post:	22-Jan-2018
Category:	Engineering
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Database Programming using SQL

Engineering