CONCEPT ON STRUCTURED QUERY LANGUAGE (SQL) By: Rohan Byanjankar Sainik Awasiya Mahavidyalaya, Sallaghari, Bhaktapur

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1 CONCEPT ON STRUCTURED QUERY LANGUAGE (SQL) By: Rohan Byanjankar Sainik Awasiya Mahavidyalaya, Sallaghari, Bhaktapur 1

2 Structured Query Language Structured Query Language (SQL) is the special purposed programming language, Main purpose of SQL to access data in Relational Database Management System, RDBMS is the most revered DBMS, and basis for SQL, The data in RDBMS are recorded in relations or table, Relation is the pre-defined rows and column, where column contains attributes, and tuples in rows, Oracle, SQL Server, MySQL are the examples 2

3 Major Two Languages in RDBMS Data Definition Language Data Manipulation Language 3

4 Data Definition Language (DDL) One of the fundamental requirements of SQL, One is dumb in the SQL without knowledge of DDL, Backbone of SQL, Helps to develop overall design of database, Helps to create, delete, and modify the database schema, Not frequently used as database schema is not frequently changed, 4

5 Basic DDL Commands Create Use Drop Alter 5

6 Create Command One of the fundamental commands, Use to establish many new independent database in DBMS, Use to create table within newly established database or existing database, Syntax: - CREATE DATABASE SAMB - CREATE TABLE Students 6

7 Use Command One of the fundamental commands, Helps to work on the newly established or created database, Syntax: - USE SAMB Drop Command One of the DDL commands, Used to delete column of a table, entire table, and entire database, We must use drop command with intense care, Syntax: - DROP TABLE Student - DROP DATABASE SAMB 7

8 Alter Command Falls under the category of DDL command, Used to change the structure of table without deleting or re-creating the table, Syntax: 1. ALTER TABLE Student ADD _id VARCHAR(20) 2. ALTER TABLE Student DROP COLUMN _id 8

9 Data Manipulation Language (DML) One of the fundamental requirements of SQL, DML helps to work on RDBMS, Helps to change the content of RDBMS, Helps to insert, select, update and delete the database instances, Frequently used as frequent modification is made in database, 9

10 Basic DML Command Insert Select Update Delete 10

11 Insert Command Basic DML command, Used to add new data in database, The most frequently used, Syntax: INERT INTO Student VALUES (0020, Sujita Shrestha, BBA, 16, ) INSERT INTO Student (sid, sname, grade) VALUES (0023, Smiriti KC, BBA ) 11

12 Select Command Enables to select data from database, Syntax: To select all SELECT * FROM Student To select students with name staring from S SELECT * FROM Student where sname= s% To select students according to ID in descending order SELECT * FROM Student ORDER BY sid desc 12

13 Update Command Used to update existing record in a table, Syntax: UPDATE table_name SET column1= Value1 For Example: To update salary to 1.5 times of existing salary of an employee with empid 19 UPDATE tblemployee SET salary = 1.5*salary WHERE empid= 19 13

14 Delete Command Enables us to remove the selected tuple or entire tuple without making alter to the table, Syntax: DELETE FROM table_name WHERE column1= Value1 For Example: If Student with sid 0001 is needed to be removed from Student table, then DELETE FROM Student WHERE sid=

15 SQL Views SQL View is a logical table, Created from the existing table, Virtual table based on real table, Constraints of Base table is applicable in View also. Any modification in base table is reflected in View. User can Use DML commands once the view is created. 15

16 Syntax CREATE VIEW View_name AS SELECT column1, column2, column3 FROM Table_1 WHERE column3= Value1 For Example: To create view from table Product (Pid, Pname, Cost Price, Selling Price, Manu_date, Exp_date, Category) to Beverage Department CREATE VIEW Beverage AS SELECT Pid, Pname, Selling Price, Manu_date, Exp_date FROM Product WHERE Category= Beverage 16

17 Product Pid Pname Cost Price Selling Price Manu_date Exp_date Category 001 Parle-G General 002 Coca-Cola Beverage 003 Toberg Beverage 004 Sunflow Oil General CREATE VIEW Beverage AS SELECT Pid, Pname, Selling Price, Manu_date, Exp_date FROM Product WHERE Category= Beverage Beverage Beverage Department Pid Pname Selling Price Manu_date Exp_date 002 Coca-Cola Toberg

18 Index A database index is a data structure that improves the speed of data retrieval operations on a database table, used to quickly locate data without having to search every row Syntax: CREATE INDEX index_name ON Table_name (column1) 18

19 Library Contd ISBN Bname Price Author The Old Man and The Sea Rs. 97 Ernest Hemingway Far from the Madding Crowd Rs. 200 Thomas Hardy One The Call Center Rs. 200 Chetan Bhagat For Example: To create INDEX on table Library (ISBN, Bname, Price, Author) CREATE INDEX Book_index ON Library (ISBN) 19

20 Aggregate Function Those functions that perform a calculation on a set of values and return a single value. MAX, MIN, AVG, COUNT are the examples Syntax: 1. SELECT Column1, MAX(Column2) AS MAX_Price FROM Tbleproduct 2. SELECT Column1, MIN(Column2) AS MIN_Price FROM Tbleproduct 3. SELECT Column1, AVG(Column2) AS AVG_Price FROM Tbleproduct 20

21 Product Contd Pid Pname Cost_Price Selling_Price Manu_date Exp_date Category 001 Parle-G General 002 Coca-Cola Beverage 003 Tuborg Beverage 004 Sunflow Oil General SELECT Category, MAX(Selling_Price) AS MAX_SP FROM Product GROUP BY Category Category MAX_SP Beverage 220 General

22 Joins SQL join is the operation that enables us to get the combined Values of attributes of two tables, The most common type of join is Inner Join. Syntax: SELECT column1, column2, column3, column5, column6 FROM Table1 INNER JOIN Table2 ON Table1.Column1=Table2.column5 Note: Data type of column1 and column5 must be identical 22

23 ISBN Bname Price Author The Old Man and The Sea Rs. 97 Ernest Hemingway Far from the Madding Crowd Rs. 200 Thomas Hardy One The Call Center Rs. 200 Chetan Bhagat Library ID Sname Grade ISBN Sanjay Sharma BBA Sushil Shrestha BSC Samikshaya Sharma BBA Student SELECT ISBN, Bname, ID, Sname, Grade, ISBN1 FROM Library INNER JOIN Student ON Library.ISBN= Student.ISBN1 ISBN Bname ID Sname Grade One The Call Center 0001 Sanjay Sharma BBA The Old Man and The Sea 0002 Sushil Shrestha BSC Far from the Madding Crowd 0030 Samikshaya Sharma BBA 23

24 SQL Question: Create Table Student with following attributes: ID Number Primary Key Name Text Not Null and length<40 Age Number >17 and <25 Grade Text BBA or BSC Not Null Text Unique Not Null Contact Text Not Null Length= 7 or 10 Address Text Not Null CREATE TABLE Student ( ID INT, Sname VARCHAR (50) NOT NULL, Age INT, Grade VARCHAR (8) NOT NULL, _id VARCHAR (30) UNIQUE NOT NULL, Contact VARCHAR (13) NOT NULL, Address VARCHAR (30) NOT NULL, CONSTRAINT pk_id PRIMARY KEY (ID), CONSTRAINT ch_values CHECK (LEN(Sname)<40), CONSTRAINT ch_values1 CHECK(Grade IN ( BBA, BSC )), CONSTRAINT ch_values2 CHECK (LEN(Contact)=7 OR LEN(Contact)=10)); 24

ASSIGNMENT NO 2. Objectives: To understand and demonstrate DDL statements on various SQL objects

ASSIGNMENT NO 2. Objectives: To understand and demonstrate DDL statements on various SQL objects ASSIGNMENT NO 2 Title: Design and Develop SQL DDL statements which demonstrate the use of SQL objects such as Table, View, Index, Sequence, Synonym Objectives: To understand and demonstrate DDL statements