MySQL Introduction. By Prof. B.A.Khivsara

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1 MySQL Introduction By Prof. B.A.Khivsara Note: The material to prepare this presentation has been taken from internet and are generated only for students reference and not for commercial use.

2 Outline Design and Develop SQL DDL statements which demonstrate the use of SQL objects such as Table, View, Index, Sequence, Synonym

3 Table RollNo Name Address 1 Bhavana Nashik 2 Jiya Pune Table Name: Student

View View is a logical table. It is a physical object which stores data logically. View just refers to data that is tored in base tables. A view is a logical entity.

4 View View is a logical table. It is a physical object which stores data logically. View just refers to data that is tored in base tables. A view is a logical entity. It is a SQL statement stored in the database in the system tablespace. Data for a view is built in a table created by the database engine in the TEMP tablespace. View Name: St_View created on table Students RollNo Name 1 Bhavana 2 Jiya

5 Index Database index, or just index, helps speed up the retrieval of data from tables. When you query data from a table, first MySQL checks if the indexes exist, then MySQL uses the indexes to select exact physical corresponding rows of the table instead of scanning the whole table.

6 Index of Book- an Example

7 Sequence you can create a column that contains a sequence of numbers (1, 2, 3, and so on) by using the AUTO_INCREMENT attribute. Sequence Bill No Date Particulars Amount 101 2/3/2017 Mixer /3/2017 T.V /3/2017 Speaker 1600

8 Synonym A synonym is an alternative name for objects such as tables, views, sequences, stored procedures, and other database objects. Eg. Nickname or short name of any person Note: Synonyms are not possible in MySQL but possible with oracle.

9 Commands Types DDL Data Definition Language DML Data Manipulation Language DCL Data Control Language TCL Transaction Control Language

10 Commands Types

11 DDL- Data Definition Language DDL statements or commands are used to define and modify the database structure of your tables or schema. Some commands of DDL are: CREATE to create table (objects) in the database ALTER alters the structure of the database DROP delete table from the database TRUNCATE remove all records from a table, including all spaces allocated for the records are removed COMMENT add comments to the data dictionary RENAME rename a table

12 DDL Commands for Table Create table Show tables Describe table Alter table Truncate table Drop table Rename

13 DDL Commands for Table Create table Syntax Create table table_name (Col_name1 data_type(size), Col_name2 data_type(size), )) Example Create table Stud(rno number(4),name varchar2(20), DOB date));

14 DDL Commands for Table Describe table Syntax desc table_name; Example desc Stud;

15 DDL Commands for Table Show tables This will list the tables in the current database: Syntax show tables; Example mysql> show tables; customers orders 2 rows in set (0.00 sec)

16 DDL Commands for Table Alter table (add or modify) Syntax alter table table_name add/modify/drop column_name data_type(size) Example Alter table stud add age int(3); Alter table stud modify name varchar2(30); Alter table stud modify name char(20); Alter table stud drop column age;

17 DDL Commands for Table Truncate Table used to delete complete data from an existing table. Syntax TRUNCATE TABLE table_name; Example mysql> TRUNCATE TABLE stud;

18 DDL Commands for Table Rename Table used to rename table. Syntax RENAME TABLE tbl_name TO new_tbl_name Example mysql> RENAME TABLE stud TO student ;

19 Constraints Constraints are the set of rules defined on tables to ensure data integrity. Primary key Not null Default Unique Check Foreign key/reference key

20 Constraints- Unique The UNIQUE constraint in MySQL does not allow to insert a duplicate value in a column. Syntax CREATE TABLE table_name (col_name data_type (size) Unique); Example CREATE TABLE Stud (Rno number(4) Unique);

21 Constraints- Not Null A NOT NULL constraint means that a data row must have a value for the column specified as NOT NULL. Syntax CREATE TABLE table_name (Col_name Data_type(size)not null,... ); Example Create table stud (rollno number(4),name varchar2(20)not null);

22 Constraints- Primary key Each table must normally contain a column or set of columns that uniquely identifies rows of data that are stored in the table. This column or set of columns is referred to as the primary key. A table can have only one primary key. Multiple columns can be clubbed under a composite primary key. Primary key columns is combination of NOT NULL and UNIQUE. Syntax CREATE TABLE table_name ( Col_name Data_type(size)CONSTRAINT constraint_name PRIMARY KEY,... ); Example Create table stud (rollno number(4)constraint pk1 primary key,name ) Create table stud (rollno number(4) primary key, name.)

23 Constraints- Default In a MySQL table, while inserting data into a table, if no value is supplied to a column, then the column gets the value set as DEFAULT. Syntax CREATE TABLE table_name (col_name data_type(size) DEFAULT default_value ); Example CREATE TABLE Stud (rno number(4),name varchar2(20), addr varchar(30) DEFAULT Chandwad );

24 Constraints- Check In a MySQL table, A CHECK constraint controls the values in the associated column. The CHECK constraint determines whether the value is valid or not. Syntax CREATE TABLE table_name (col_name data_type(size) Check (condition) ); Example CREATE TABLE Stud (rno number(4) CHECK (rollno BETWEEN 1 AND 60)); CREATE TABLE Stud (age number(4) CHECK (age>18));

25 Constraints- FOREIGN KEY A FOREIGN KEY in MySQL creates a link between two tables by one specific column of both tables. The specified column in one table must be a PRIMARY KEY and referred by the column of another table known as FOREIGN KEY. Syntax Create table table_name(col_name data_type(size)references table_name(col_name)); Example Createtable stud1 (rollno number(4) references stud(rno));

26 Constraints- after table creation and drop constraint You can also add constraint after table creation using alter table option Example Alter table stud add constraint prk1 primary key(rollno); You can also drop constraint using Drop command & name of constraint Example Drop constraint prk1;

27 DDL Commands for Table Drop table Syntax Drop table table_name; Example Drop table stud;

28 DDL Commands for Index Create Index Show Index Drop Index

29 DDL Commands for Index Create Index Syntax 1> Create Index index_name on table_name(column_name) 2> Alter table table_name add index index_name (column_name) Example 1> Create Index n1 on Stud(Name) 2> Alter table Stud add Index n1 (name)

30 DDL Commands for Index Show Index Syntax Show Index from table_name Example Show Index from Stud;

31 DDL Commands for Index Drop Index Syntax Alter table table_name drop Index index_name Example Alter table Stud drop Index n1;

32 DDL Commands for View Create View Show View Drop View

33 DDL Commands for View Create View Syntax Create View view_name as select col_name1,col_name2 from table_name [where <condition>] Example 1>Create view v1 as select name from stud; 2>Create view v2 as select name from stud where addr= Nashik ;

34 DDL Commands for View Show View Syntax Select col_name1,.. from View_name [where condition] Example Select * from v1;

35 DDL Commands for View Drop View Syntax Drop View view_name Example Drop View v1;

36 Sequence- Using AUTO_INCREMENT Column AUTO_INCREMENT Syntax CREATE TABLE table_name ( column1 datatype NOT NULL AUTO_INCREMENT,.); ALTER TABLE table_name AUTO_INCREMENT = start_value; Example CREATE TABLE Bills ( Bill_No INT(11) NOT NULL AUTO_INCREMENT, name varchar2(20)); ALTER TABLE Bills AUTO_INCREMENT = 1001;

37 Assignment Create one table employee with fields Eno primary key and apply sequence starts with 101 Ename not null Address default Nashik Joindate Post Salary check > 5000 Create another table emp_proj with fields Eno- forign key Project_name Loc Create Index on Ename field of employee table Create View on employee table to show only Employee name, it s post and salary.

38 References

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