Pl sql content

Content
• PL/SQL Introduction
• What is Data
• What is information
• Database
• Database of management studies
• Application of DBMS
• Types of DBMS
• SQL
• SQL Command
• Sample SQL creating table

PL/SQL stands for “Procedural Language extensions to the structured
query Language”. SQL is a popular language for both querying and updating data in
the relational database management systems (RDBMS). PL/SQL adds many
procedural constructs to SQL language to overcome some limitations of SQL.
PL/SQL
One can create a PL/SQL unit such as procedures, functions, packages, triggers,
and types, which are stored in the database for reuse by applications.

What is Data
• A collection of raw facts and figures
• Raw Material that can be processed by
computing machine
• A collection of facts from which conclusions
may be drawn
• Data can be represented in the form of
numbers and words which can be stored in
computer’s language

What is information
• Systematic and meaningful form of data
• Knowledge acquired through study or experience
• Information helps human beings in their decision making

Database
• A repository of logically related and similar data
• An organized collection of related information so that it
can easily be accessed, managed and updated
Eg:
• Dictionary
• Airline Database
• Student Database
• Library
• Railways Timetable
• YouTube(All Songs of Rahul Vaidya)

What is DBMS
• DBMS stands for Database Management System
• DBMS is a software system for creating , organizing and managing
the database
• It provides an environment to the user to perform operations on the
database for creation, insertion, deletion, updating and retrieval of
data

Why Use a DBMS
• Data independence and efficient access
• Reduced application development time
• Data integrity and security
• Uniform data administration
• Concurrent access, recovery from crashes.

DifferentpeoplebehindDBMS
• Database Administrator(DBA)- The DBA is responsible for authorizing access to the database, for
coordinating and monitoring its use, an for acquiring software and hardware resources as need
• Database Designers - Database designers are responsible for identifying the data to be stored in the database
or choosing appropriate structures to represent and store this data. These tasks are mostly undertaken before
the database is actually implemented and populated with data
• End Users –
• Casual end users,
• naïve or parametric end users,
• Sophisticated end users,
• stand-alone users
• System Analysts and Application Programmers – Application programmers implement these specifications
as programs, then they test, debug, document, and maintain theses canned transactions
• DBMS Designers and implementers : are persons who design and implement the DBMS modules and
interfaces as a software package.
• Tool Developers : They include package for database design, performance monitoring, natural language or
graphical interfaces, prototyping ,simulation , and test data generation
• Operators and Maintenance Personnel : are the system administration personnel who are responsible for
the actual running and maintenance of the hardware and software environment for the database system

Application of DBMS
Sector Use of DBMS
Banking For customer information, account activities, payments,
deposits, loans, etc.
Airlines For reservations and schedule information.
Universities For student information, course registrations, colleges and
grades.
Telecommunication It helps to keep call records, monthly bills, maintaining
balances, etc.
Finance For storing information about stock, sales, and purchases of
financial instruments like stocks and bonds.
Sales Use for storing customer, product & sales information.
Manufacturing It is used for the management of supply chain and for tracking
production of items. Inventories status in warehouses.
HR Management For information about employees, salaries, payroll, deduction,
generation of paychecks, etc.

Types of DBMS
Hierarchical DBMS
In a Hierarchical database, model data is organized in a tree-like structure. Data is Stored Hierarchically (top down or bottom
up) format. Data is represented using a parent-child relationship. In Hierarchical DBMS parent may have many children, but
children have only one parent.
Network Model
The network database model allows each child to have multiple parents. It helps you to address the need to model more complex
relationships like as the orders/parts many-to-many relationship. In this model, entities are organized in a graph which can be
accessed through several paths.
Relational model
Relational DBMS is the most widely used DBMS model because it is one of the easiest. This model is based on normalizing data
in the rows and columns of the tables. Relational model stored in fixed structures and manipulated using SQL.
Object-Oriented Model
In Object-oriented Model data stored in the form of objects. The structure which is called classes which display data within it. It
defines a database as a collection of objects which stores both data members values and operations.

What is SQL
SQL is used to communicate with a database. According to ANSI (American
National Standards Institute), it is the standard language for
relational database management systems. SQL statements are used to perform
tasks such as update data on a database, or retrieve data from a database.

Fact of SQL
SQL was developed at IBM by Donald D. Chamberlin
and Raymond F Boyce in the early 1970s
It was initially called SEQUEL(Structured English Query
Language)
SQL is a powerful language that uses simple English
sentences
SQL is a Declarative Language

• Structure Query Language(SQL) is a database query
language used for storing and managing data in Relational
DBMS.
• Today almost all RDBMS(MySql, Oracle, Infomix,
Sybase, MS Access) use SQL as the standard database
query language.
• SQL is used to perform all types of data operations in
RDBMS.

SQL Command
DDL: Data Definition Language
Data Definition Language (DDL) statement are used to define the database structure or
schema
Some example
CREATE- to create objects in the database
ALTER- alters the structure of the database
DROP- delete objects from the database
TRUNCATE- remove all records from a table, including all space allocated for the
records are removed
COMMENT – add comments to the data dictionary
RENAME-rename an object

DML: Data Manipulation Language
Data Manipulation Language(DML) statement are used for managing data
within schema objects
SELECT- Retrieve data from the a database
INSERT- Insert data into a table
UPDATE- Updates existing data within a table
DELETE - deletes all records from a table, the space for the records remain

• TCL: Transaction Control Language
(These commands are to keep a check on other commands and their
affect on the database.(commit, rollback)
• DCL: Data Control Language(grant: permission)
• DQL: Data Query Language (select)

create table students(regno number(10), name varchar2(15), major varchar2(8));
desc students;
insert into students values('03','naveen','maths')
select * from students
Select regno ,major from students
delete students
alter table studentss rename to stud;
drop table stud;
desc stud;
Sample SQL creating table

SQL and PL/SQL execution
STEP-01

Exercise-01
1.Write a SQL statement to display all the information of all salesmen. Sample table:
salesman

Exercise-01- Solution
1.Write a SQL statement to display all the information of all salesmen. Sample table:
salesman
create table salesmen(sales_id number(10), name varchar(12), city varchar(10),
commission number(20));
insert into salesmen values(500,'james Hoog','New york',0.15);

Exercise-02
Table name : workers

Solution
create table Worker1(worker_id number(10),firstname char(23),lastname char(23),salary
number(15),department char(24));
insert into Worker1 values (001, 'Monika', 'Arora', 100000,'HR');
select * from Worker1;

Disadvantages of SQL
• SQL doesn’t provide the programmers with a technique of condition checking, looping and
branching.
• SQL statements are passed to Oracle engine one at a time which increases traffic and decreases
speed.
• SQL has no facility of error checking during manipulation of data.
• For SQL need training to an excess database.
• SQL can be handled by an expert user or programmer.
• It occupies some space i.e extra memory location for each record.
• It is a command based language.
• It is platform dependent language.

Introduction to PL/SQL
PL/SQL stands for “Procedural Language extensions to the structured Query Language
A procedural language is a type of computer programming language that specifies a series of well-structured steps and procedures within its
programming context to compose a program. It contains a systematic order of statements, functions and commands to complete a
computational task or program.
The PL/SQL programming language was developed by Oracle Corporation in the late 1980s as procedural
extension language for SQL and the Oracle relational database.
Following are certain notable facts about PL/SQL −
• PL/SQL is a completely portable, high-performance transaction-processing language.
• PL/SQL provides a built-in, interpreted and OS independent programming environment.
• PL/SQL can also directly be called from the command-line SQL*Plus interface.
• Direct call can also be made from external programming language calls to database.
• PL/SQL's general syntax is based on that of ADA and Pascal programming language.
• Apart from Oracle, PL/SQL is available in TimesTen in-memory database and IBM DB2.

Features of PL/SQL
Portable:
PL/SQL applications can be executed with all types of operating system where we have oracle
installed.
Efficient:
All sorts of calculations can be efficiently performed by PL/SQL without the use of oracle
engine. This improves transaction performance.
Error-checking
PL/SQL allows error-checking and displays user-friendly messages when error occurs.
Development tool:
PL/SQL supports execution of SQL statements along with the functionality of variable declaration,
conditional statements, looping and branching, procedures, functions and triggers.
Exception Handling:
PL/SQL code is capable of handling exceptions that can affect the flow of program, hence helps in
making the code more reliable

• For example, consider we have a School Management System database and
we want to see the list of students who took admission in last 5 years in
school and the fees deposited by them.
• And at the same time we want to add the total amount of salary money given
to the teaching and non-teaching staff. We cannot fetch these records by just
executing SQL queries, we might be able to gather the data but it would
require multiple SQL queries.
• On the other hand if we use PL/SQL, we can write procedures or methods in
PL/SQL program to execute complex logic on a database.
• Another advantage is that we can also detect errors easily as it displays user-
friendly messages and it even supports exception handling.

SQL PL/SQL
SQL is a single query that is used to
perform DML and DDL operations.
PL/SQL is a block of codes that used
to write the entire program blocks/
procedure/ function, etc.
It is declarative, that defines what
needs to be done, rather than how
things need to be done.
PL/SQL is procedural that defines
how the things needs to be done.
Execute as a single statement. Execute as a whole block.
Mainly used to manipulate data. Mainly used to create an application.
Cannot contain PL/SQL code in it.
It is an extension of SQL, so it can
contain SQL inside it.
Differences between SQL and PL/SQL:

Architecture of PL/SQL
The PL/SQL architecture mainly consists of following three components:
– PL/SQL block
– PL/SQL Engine
– Database Server
PL/SQL block
This is the component which has the actual PL/SQL code.
This consists of different sections to divide the code logically (declarative section for declaring
purpose, execution section for processing statements, exception handling section for handling
errors)
It also contains the SQL instruction that used to interact with the database server.
All the PL/SQL units are treated as PL/SQL blocks, and this is the starting stage of the architecture
which serves as the primary input

Following are the different type of PL/SQL units.
Anonymous Block
Function
Library
Procedure
Package Body
Package Specification
Trigger
Type
Type Body

PL/SQL Engine
• PL/SQL engine is the component where the actual processing of the codes takes place.
• PL/SQL engine separates PL/SQL units and SQL part in the input.
• The separated PL/SQL units will be handled by the PL/SQL engine itself.
• The SQL part will be sent to database server where the actual interaction with database takes place.
• It can be installed in both database server and in the application server

Database Server:
• This is the most important component of Pl/SQL unit which stores the data.
• The PL/SQL engine uses the SQL from PL/SQL units to interact with the database server.
• It consists of SQL executor which parses the input SQL statements and execute the same.

Typically, each block performs a logical action in the
program. A block has the following structure:

DECLARE
• Declare section starts with DECLARE keyword in which variables, constants, records as cursors can be declared which stores
data temporarily. It basically consists definition of PL/SQL identifiers. This part of the code is optional.
EXECUTION SECTION
• Execution section starts with BEGIN and ends with END keyword.
• This is a mandatory section and here the program logic is written to perform any task like loops and conditional statements.
• It should have at least one executable line of code, which may be just a NULL command to indicate that nothing should be
executed.
EXCEPTION
• Exception section starts with EXCEPTION keyword.
• This section is optional which contains statements that are executed when a run-time error occurs.
• Any exceptions can be handled in this section.

PL/SQL SET Serveroutput ON
• Whenever you start Oracle SQL (PL/SQL) at that time you must have to write the "SET Serveroutput ON"
command.
• PL/SQL program execution into Oracle engine so we always required to get serveroutput result and display
into the screen otherwise result can't be display.

PL/SQL anonymous block example
• The following example shows a simple PL/SQL anonymous block with one executable
section.
To run the code from the SQL command line, you may need to type / at the beginning of the first
blank line after the last line of the code.
When the above code is executed at the SQL prompt, it produces the following result −
Hello There
PL/SQL procedure successfully completed.

The PL/SQL Comments
• The PL/SQL supports single-line and multi-line comments.
• All characters available inside any comment are ignored by the PL/SQL compiler.
• The PL/SQL single-line comments start with the delimiter -- (double hyphen) and multi-line comments are enclosed by /*
and */.
Syntax Using -- symbol
The syntax for creating a SQL comment in Oracle using -- symbol is:
Syntax Using /* and */ symbols
The syntax for creating a SQL comment in Oracle using /* and */ symbols is:

Example - Comment on Multiple Lines

PL/SQL has two kinds of data types: scalar and composite. The scalar types are types that store single values
such as number, Boolean, character, and datetime whereas the composite types are types that store multiple
values, for example array, record and collection.
PL/SQL Data types
S.No Category & Description
1
Scalar
Single values with no internal components, such as a NUMBER,
DATE, or BOOLEAN.
2
Large Object (LOB)
Pointers to large objects that are stored separately from other data items,
such as text, graphic images, video clips, and sound waveforms.
3
Composite
Data items that have internal components that can be accessed
individually. For example, collections and records.
4
Reference
Pointers to other data items.
PL/SQL Scalar Data Types and Subtypes

S.No Date Type & Description
1
Numeric
Numeric values on which arithmetic operations are performed.
2
Character
Alphanumeric values that represent single characters or strings of
characters.
3
Boolean
Logical values on which logical operations are performed.
4
Datetime
Dates and times.
PL/SQL Scalar Data Types and Subtypes

PL/SQL Variables
A variable is a meaningful name which facilitates a programmer to store data temporarily during the execution of
code. It helps you to manipulate data in PL/SQL programs. It is nothing except a name given to a storage area. Each
variable in the PL/SQL has a specific data type which defines the size and layout of the variable's memory.
The syntax for a variable declaration is as follows:
variable_name datatype [NOT NULL] [:= initial_value];
Naming rules for PL/SQL variables
• The variable in PL/SQL must follow some naming rules like other programming languages.
• The variable_name should not exceed 30 characters.
• The name of the variable must begin with ASCII letter. The PL/SQL is not case sensitive so it could be either
lowercase or uppercase. For example: v_data and V_DATA refer to the same variables.
• You should make your variable easy to read and understand, after the first character, it may be any number,
underscore (_) or dollar sign ($).

DECLARE
a integer := 30;
b integer := 40;
c integer;
f real;
BEGIN
c := a + b;
dbms_output.put_line('Value of c: ' || c);
f := 100.0/3.0;
dbms_output.put_line('Value of f: ' || f);
END;
After the execution, this will produce the following result:
Value of c: 70
Value of f: 33.333333333333333333
Example of initializing variable

DECLARE
-- Global variables
num1 number := 95;
num2 number := 85;
BEGIN
dbms_output.put_line('Outer Variable num1: ' || num1);
dbms_output.put_line('Outer Variable num2: ' || num2);
DECLARE
-- Local variables
num1 number := 195;
num2 number := 185;
BEGIN
dbms_output.put_line('Inner Variable num1: ' || num1);
dbms_output.put_line('Inner Variable num2: ' || num2);
END;
END;
/
After the execution, this will produce the following result:
Outer Variable num1: 95
Outer Variable num2: 85
Inner Variable num1: 195
Inner Variable num2: 185

PL/SQL Constants
A constant is a value used in a PL/SQL block that remains unchanged throughout the program. It is a user-
defined literal value. It can be declared and used instead of actual values.
Suppose, you have to write a program which will increase the salary of the employees upto 30%, you can declare
a constant and use it throughout the program. Next time if you want to increase the salary again you can change
the value of constant than the actual value throughout the program.
Syntax to declare a constant:
constant_name CONSTANT datatype := VALUE;
Constant_name:it is the name of constant just like variable name. The constant word is a reserved
word and its value does not change.
VALUE: it is a value which is assigned to a constant when it is declared. It can not be assigned later.

DECLARE
-- constant declaration
pi constant number := 3.141592654;
-- other declarations
radius number(5,2);
dia number(5,2);
circumference number(7, 2);
area number (10, 2);
BEGIN
-- processing
radius := 9.5;
dia := radius * 2;
circumference := 2.0 * pi * radius;
area := pi * radius * radius;
-- output
dbms_output.put_line('Radius: ' || radius);
dbms_output.put_line('Diameter: ' || dia);
dbms_output.put_line('Circumference: ' || circumference);
dbms_output.put_line('Area: ' || area);
END;
/
After the execution of the above code at SQL prompt, it will produce the following result:.
Radius: 9.5
Diameter: 19
Circumference: 59.69
Area: 283.53
Pl/SQL procedure successfully completed.

Literals Examples
Numeric 75125, 3568, 33.3333333 etc.
Character 'A' '%' '9' ' ' 'z' '('
String Hello JavaTpoint!
Boolean TRUE, FALSE, NULL etc.
Date and Time '26-11-2002' , '2012-10-29 12:01:01'
PL/SQL Literals
Literals are the explicit numeric, character, string or boolean values which are not represented by an
identifier. For example: TRUE, NULL, etc. are all literals of type boolean. PL/SQL literals are case-
sensitive. There are following kinds of literals in PL/SQL:
•Numeric Literals
•Character Literals
•String Literals
•BOOLEAN Literals
•Date and Time Literals

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