sql

Structured Query Language (SQL)

1Rushdi Shams, Lecturer, Dept of CSE, KUET, Bangladesh

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Rushdi Shams, Dept of CSE,

KUET

Basics of Table Table is a bucket where you pour data. Data in a specific table is associated with

all other items in that table. In a table, there are basically 3 things-1. Rows / Records / Tuples2. Columns / Attributes / Fields3. Data

3Rushdi Shams, Dept of CSE, KUET

Basics of Table

In the table, the column goes on in a horizontal fashion.

ISBN, AUTHOR, PUBLISHER, TITLE, GENRE, PRINTED are the column names for this table

4Rushdi Shams, Dept of CSE, KUET

Basics of Table

In the table, the row goes on in a vertical fashion. Every row in this table has data for ISBN, AUTHOR,

PUBLISHER, TITLE, GENRE, PRINTED

5Rushdi Shams, Dept of CSE, KUET

Basic of Table

Books contain relatively disorganized data Organize information using model Resulting in a neatly structured set of rows and

columns

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Rushdi Shams, Dept of CSE,

KUET

Relation / Table In relational data model, the table is also called

relation. There are set of rules that are applied on the relations. You must have to know them.

1. A database contains many relations. Every relations in a database must have distinct names

2. Every column in a relation must have distinct names3. Every entries in a column must be in the same domain4. The ordering of columns in a relation is insignificant

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Rushdi Shams, Dept of CSE,

KUET

Relation / Table (continued)

5. Duplicate rows are not allowed in a relation

6. The ordering of rows is insignificant7. Multiple values are not allowed in the cells

of a relation8. 2 rows in a relation may contain the same

value for 1 columns but not in all (deviation of 5)

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Rushdi Shams, Dept of CSE,

KUET

Terminology The number of rows in a table is called

Cardinality The number of columns in a table is called

Degree

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Rushdi Shams, Dept of CSE,

KUET

Languages in Database Systems Data Definition Language (DDL) Used to create and modify the structure of

database objects CREATE ALTER DROP

DDL commands execute as soon as they are issued, and do not need to be explicitly saved

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Rushdi Shams, Dept of CSE,

KUET

Languages in Database Systems Data Modification Language (DML) Used to insert, view, and modify database data

INSERT UPDATE DELETE SELECT

DML commands need to be explicitly saved or rolled back

COMMIT ROLLBACK

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Rushdi Shams, Dept of CSE,

KUET

Languages in Database Systems Data Control Language (DCL)

Privileges, Access Control, Administrative Rights

Data Definition Language (DDL)Data Definition Language (DDL)

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Creating a table

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Creating a table

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Dropping a table

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DROP TABLE table_name; DROP TABLE cars; DROP TABLE specs; DROP TABLE stock;

Adding a column to a table

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Adding columns to a table

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Modifying a single column on a table

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Modifying columns on a table

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Dropping columns on a table

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Renaming columns on a table

Data Modification Language (DML)Data Modification Language (DML)

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Inserting data into table

REMEMBER- when you are inserting values that are varchar, char or other string types (if any) then you will have to put ‘’ around that value (e.g. ‘value_for_column_X’).

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Inserting data into table

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Showing data in a table

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Updating data in a table

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Deleting row from a table

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If you do not put WHERE clause, while using it with DELETE statement then all the data in that table will be deleted. SO, BE CAREFUL!

Data Control Language (DCL)Data Control Language (DCL)

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Rushdi Shams, Dept of CSE,

KUET

Types of Database Privileges System Privileges

Control the operations that the user can perform within the database○ Connecting to the database, creating new tables, shutting

down the database, etc. Object Privileges

Granted on individual database objectsControls operations that a user can perform on a

specific object (insert data, delete data, etc.)When you create an object in your user schema, you

can then grant object privileges on that object to other database users

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Rushdi Shams, Dept of CSE,

KUET

Database Objects An Oracle database consists of multiple user

accounts Each user account owns database objects

TablesViewsStored programs

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Rushdi Shams, Dept of CSE,

KUET

Oracle Naming Standard Oracle database objects must adhere to the

Oracle Naming Standard1 to 30 characters longMust begin with a characterCan contain characters, numbers, and the

symbols $, _ , and #

32Rushdi Shams, Dept of CSE, KUET

Creating New User Accounts Done by DBA Syntax:

CREATE USER username IDENTIFIED BY password;

33Rushdi Shams, Dept of CSE, KUET

Trying to access the database As we have created a new user and assigned his

password, should we be able to log into the database with the username and password?

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Rushdi Shams, Dept of CSE,

KUET

The Answer

35Rushdi Shams, Dept of CSE, KUET

Granting System Privileges Done by DBA Syntax:

GRANT privilege1, privilege2, … TO username;

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Rushdi Shams, Dept of CSE,

KUET

So, now can you log in? Yes, you can!

37Rushdi Shams, Dept of CSE, KUET

Example Oracle System Privileges

PrivilegePrivilege LevLevelel

PurposePurpose

CREATE SESSIONCREATE SESSION UseUserr

Connecting to databaseConnecting to database

CREATE TABLE CREATE TABLE UseUserr

Creating tables in current user Creating tables in current user schemaschema

UNLIMITED UNLIMITED TABLESPACETABLESPACE

UseUserr

Allows user to create schema Allows user to create schema objects using as much space as objects using as much space as neededneeded

CREATE USERCREATE USER DBDBAA

Creating new usersCreating new users

GRANT ANY GRANT ANY PRIVILEGEPRIVILEGE

DBDBAA

Granting system privileges to Granting system privileges to usersusers

CREATE ANY TABLECREATE ANY TABLE DBDBAA

Creating tables in any user Creating tables in any user schemaschema

DROP ANY TABLEDROP ANY TABLE DBDBAA

Dropping tables in any user Dropping tables in any user schemaschema

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Rushdi Shams, Dept of CSE,

KUET

Granting another privilege

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Rushdi Shams, Dept of CSE,

KUET

Can you create table yet?

40Rushdi Shams, Dept of CSE, KUET

The Reason You have granted your user to create session (log in)

and to create table. But, it is to create on your default SYSTEM database. Therefore, you will have to grant another privilege to your user.

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Rushdi Shams, Dept of CSE,

KUET

… & The Solution

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Rushdi Shams, Dept of CSE,

KUET

Database Roles Role is a database object that can be

assigned system privileges Role is then assigned to a user, and the user

inherits the role’s privileges Used to easily assign groups of related

privileges to users

43Rushdi Shams, Dept of CSE, KUET

Creating a Role Syntax:CREATE ROLE role_name;

44Rushdi Shams, Dept of CSE, KUET

Granting Privilege to RoleGRANT privilege1, privilege2, … TO role_name;

45Rushdi Shams, Dept of CSE, KUET

Assigning Role to the User Syntax:GRANT role_name TO user_name;

46Rushdi Shams, Dept of CSE, KUET

Revoking System Privileges Syntax:REVOKE privilege1, privilege2, …FROM username;

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Rushdi Shams, Dept of CSE,

KUET

What Happens Next?

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Rushdi Shams, Dept of CSE,

KUET

Oracle Data Types Data type: specifies type of data stored in a

field Date, character, number, etc.

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Rushdi Shams, Dept of CSE,

KUET

Character Type Data Type VARCHAR2

Variable-length character strings Maximum of 4,000 characters Must specify maximum width allowed Example declaration:student_name VARCHAR2(30)

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Rushdi Shams, Dept of CSE,

KUET

Character Type Data Type CHAR

Fixed-length character data Maximum size 2000 characters Must specify maximum width allowed Example declaration:student_gender CHAR(1)

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Rushdi Shams, Dept of CSE,

KUET

Character Type Data Type NCHAR

Used for alternate alphabets

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Rushdi Shams, Dept of CSE,

KUET

Number Data Type NUMBER

stores values between 10-130 and 10126

General declaration format:variable_name NUMBER(precision, scale)

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Rushdi Shams, Dept of CSE,

KUET

Number Data Type Number type (integer, fixed point, floating

point) specified by precision and scale Precision: total number of digits on either side

of the decimal point Scale: number of digits to right of decimal point

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Rushdi Shams, Dept of CSE,

KUET

Number Data Type Whole number with no digits to right of

decimal point Precision is maximum width Scale is omitted

Sample declaration:s_age NUMBER (2)

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Rushdi Shams, Dept of CSE,

KUET

Fixed Point Numbers Contain a specific number of decimal places Precision is maximum width Scale is number of decimal places

Sample declaration:item_price NUMBER(5, 2)

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Rushdi Shams, Dept of CSE,

KUET

Floating Point Numbers Contain a variable number of decimal places Precision and scale are omitted

Sample declaration:s_GPA NUMBER

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Rushdi Shams, Dept of CSE,

KUET

Date Data Type DATE

Stores dates from 1/1/4712 BC to 12/31/4712 AD Stores both a date and time component

Default date format: DD-MON-YY example: 05-JUN-03

Sample declaration:s_dob DATE

SELECT command

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SELECT command

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SELECT Command

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SELECT Command

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SELECT Command

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SELECT Command

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SELECT Command

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SELECT Command

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