Basic introduction to PL/SQL

Here you will learn the tutorial of basic introduction to pl/sql with pl sql programs and example codes.

What is PL SQL?

PL/SQL (Procedural Language/Structured Query Language) is a procedural language used to extend the functionality of Oracle SQL. It is a combination of SQL with procedural programming language, allowing developers to write code to be more specific in manipulating data within Oracle databases. PL/SQL code can include SQL statements, conditional logic, loops, and other programming structures.

Discuss the basics of PL/SQL

PL/SQL (Procedural Language/Structured Query Language) is a procedural language that is used for database management to query, manipulate and control data within an Oracle Database. It is similar to SQL but has some advanced features. It is a proprietary language developed by Oracle Corporation.

The basics of PL/SQL include:

• Variables: Variables are used to store values. They can be declared and manipulated within the PL/SQL block.
• Control Structures: Control structures are used to control the flow of PL/SQL statements. Examples include IF, ELSE, LOOP, EXIT, and other statements.
• Cursors: Cursors are used to process multiple rows of data from a query. They can be used to retrieve data from the database, loop through the records, and update or delete data from the database.
• Stored Procedures: Stored procedures are stored PL/SQL programs that can be called from other programs. They can be used to perform complex operations on data and to create robust applications.
• Triggers: Triggers are used to execute a PL/SQL block when a certain event occurs. They monitor the database for changes and can be used to maintain data integrity and enforce business rules.
• Exceptions: Exceptions are used to handle errors in a PL/SQL program. They can be used to detect errors and display appropriate error messages.
• Packages: Packages are used to group related PL/SQL objects and code. They can be used to structure and modularize an application.
• Database Objects: Database objects are used to store data in the Oracle Database. Examples include tables, views, sequences, and synonyms.

What are the basic features of PL/SQL?

The basic features of pl/sql are the following:-

1. PL/SQL is a procedural language extension of SQL.
2. It is a block-structured language.
3. It supports object orientation.
4. It has a number of built-in data types, including scalar, composite, and reference.
5. It allows for easy execution of SQL statements in the same block of code.
6. It supports triggers, cursors, and exception handling.
7. It includes a wide range of libraries and packages for developing applications.
8. It can be used to store and retrieve data in relational databases.
9. It provides powerful features to help developers create efficient, secure, and reliable applications.

What are the basic operations in PL/SQL?

1. SELECT: Retrieve data from a table.
2. INSERT: Add a new row to a table.
3. UPDATE: Modify existing data in a table.
4. DELETE: Remove a row from a table.
5. EXECUTE: Execute a stored procedure or anonymous PL/SQL block.
6. DECLARE: Declare variables, constants, cursors and exceptions.
7. IF-THEN-ELSE: Control the flow of program execution.
8. LOOP: Execute a set of instructions multiple times.
9. EXCEPTION: Handle errors.

What are the basic functions in PL/SQL?

The basic functions in pl/sql are the following:-

1. Control Structures: IF statements, CASE statements, LOOP statements, GOTO statements, EXIT statements etc.
2. Cursors: DECLARE, OPEN, FETCH, CLOSE.
3. Data Manipulation Language (DML): INSERT, UPDATE, DELETE, SELECT.
4. Data Definition Language (DDL): CREATE, ALTER, DROP, RENAME.
5. Transaction Control: COMMIT, ROLLBACK, SAVEPOINT.
6. Error Handling: EXCEPTION, RAISE, PRAGMA.
7. Stored Procedures: CREATE, EXECUTE, DROP.
8. Functions: CREATE, EXECUTE, DROP.
9. Triggers: CREATE, ENABLE, DISABLE.
10. Dynamic SQL: EXECUTE IMMEDIATE.

What are the basic commands of pl sql?

The basic commands of pl sql are the followings:-

1. SELECT: Retrieves data from the database.
2. INSERT: Inserts data into the database.
3. UPDATE: Modifies existing data in the database.
4. DELETE: Deletes data from the database.
5. COMMIT: Saves the changes made to the database.
6. ROLLBACK: Undoes any changes made to the database.
7. SAVEPOINT: Creates a point in which all the changes made to the database up to that point can be rolled back.
8. DECLARE: Declares variables and cursors.
9. OPEN: Opens a cursor.
10. CLOSE: Closes a cursor.
11. FETCH: Retrieves a row from a cursor.
12. EXIT: Exits a loop or procedure.

What is architecture of PL/SQL ?

Architecture of pl/sql is displayed by the following diagram:

What are the block structures of a PL/SQL program?

The Basic Syntax of PL/SQL which is a block-structured language. This means that the PL/SQL programs are divided and written in logical blocks of code. Each block consists of three sub-parts –

Declarations

This section starts with the keyword DECLARE. It is an optional section and defines all variables, cursors, subprograms, and other elements to be used in the program.

Executable Commands

This section is enclosed between the keywords BEGIN and END and it is a mandatory section. It consists of the executable PL/SQL statements of the program. 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 Handling

This section starts with the keyword EXCEPTION. This optional section contains exception(s) that handle errors in the program.

How to create a simple PL/SQL program?

Simple Program to display ‘Welcome to the PL/SQL’ message is the following:

PL/SQL example :

PL/SQL Hello World program

DECLARE
message varchar2(20):=’Hello World’;
BEGIN
dbms_output.putline(message);
END;
/

Output:

Hello World

Discuss some of the important advantage and disadvantages of pl sql?

Advantages of PL/SQL

• Tight Integration with SQL.
• High Performance.
• High Productivity.
• Portability.
• Scalability.
• Manageability.
• Support for Object-Oriented Programming.

Disadvantages of PL/SQL

• It uses high memory.
• Roles of front-end developer and back-end developer cannot be fully separated.
• Complex and inconsistent syntax
• Lacks debugging functionality.

Conclusion 

I hope after reading this tutorial, You have understood the basic knowledge of PL/SQL like Introduction, basic features, basic functions, basic commands, PL/SQL architecture, block structure of pl/sql program, and advantages- disadvantages of pl/sql.