SQL Day1 Session1

8/6/2019 SQL Day1 Session1

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SQL and PL/SQL Essentials


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BUSINESS INFORMATION MANAGEMENT

2010 Capgemini. All rights reserved. 22

ORACLEOak Ridge Automated Computer

And Logical Engine

It is a DBMS, which manages a large amount of data in amulti user environment so that many users concurrentlyaccess the data. It Also provides security and Recovery. Itstores and manages data using relational model.

Oracle is the name of database management systemdeveloped by Oracle corporation.


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ORACLE

Oracle server manages data in the database. Users access Oracle server using SQL

commands. So Oracle server receives SQL commands from users and execute themon the database.

ORACLE SERVER

Database

CLIENT

CLIENT

SQL commands

Result


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DATABASE ARCHITECTURE

LOWER LEVEL STRUCTURE PL

LL

VL

..

..

..

..

..

..

..

..

..

U1 U2

..

..

..

SHADOWPAGE

T1 T2


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Physical Level

The Physical structure of the database is placed in Physical level.It is physically a set of operating system files. There are 3 types.

Data Files

Redo log files

Control files

These files automatically creates when database is created.


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Physical structure

Data Files It contains the data of the database. Every table that is storedin the database is a part of these files. Only Oracle Server can interpretthese data files.

Redo Log Files Every database has a set of two or more Redo Log files.The set of redo log files is known as databases redo log.

Redo Log files are used in failure recovery.

All changes made to the database are written to redo log file..

( filenames redo01.log)


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Physical Structure

Control Files Every Oracle database has a control file. It containsvital data regarding the database. It contains ( Extension of file is ctl)

Database Name

Names and locations of data files and redo log files.

Path Oracle\oradata\orcl ( to see all the 3 types of files)


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Logical Structure

Logical Structure is independent of Physical structure.Each Oracle database contains the followingcomponents.

Tablespaces

Segments

Extents

Blocks


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Tablespace

Each Database is a collection of tablespaces. For example we

can use a table space called PAYROLL to store all the datarelated to payroll application.

Every database contains SYSTEM table space. This is

automatically created when a database is created. SYSTEMtable space contains the data dictionary tables.

It is possible to make table space temporarily unavailable bymaking it off-line and make it available again by changing it toon-line. By making a tablespace off-line, DBA can take thebackup.


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SEGMENTS

Data into tablespaces comes in the form of segments. Example Tableis a segment

An Oracle database requires upto 4 types of segments

Data segments It is used to store data of tables

Index Segments used to store indexes

Rollback segments Here Undo information is stored

Temporary segments Oracle stores Temporary tables


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Extents

The storage space is allocated to segments is in the form ofExtents. Each Tablespace contains 65536 data files

N number of such Table spaces creates a database.

An extent is made with in a data file

N Number of continuous db blocks make up an Extent

Table

Table Segment

Extents

Tablespace


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QUERY PROCESS

CLIENT

DBSERVER PROCESS

CLIENTPROCESS

1

2

31 PARSING

2 EXECUTE

3 FETCH


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Oracle Instance

Every oracle database is associated with an Oracle Instance.Every time a database is started, a memory area calledSystem Global Area(SGA) or Shared Global Area is allocatedand one or more processes are started.

The combination of SGA and Oracle processes is called asOracle Instance.


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Features & Benefits

11i

ORACLE

INTERNET

Scalability

Reliability

Single Dev Model

Common Skill Sets

One ManagementInterface


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Features

Oracle Offers a comprehensive high performance

infrastructure for e-business.It is called Oracle9i.It providesevery thing needed to develop, deploy and manage InternetApplications.

Benefits

Scalability from departments to enterprise e-business sitesReliable, available and secure architecture

One development model, easy development options

Common skill sets including SQL, PL/SQL,JAVA and XMLOne Management interface for all applications

9i P d


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9i Products

9i

IAS

9i

DATABASE

There are two products. They provide a complete and simpleinfrastructure for internet applications.


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Application Server

9i Application server runs all the applications and

9i database stores our data.Oracle 9i Application server runs

Portals or web sites

Java Transactional Applications

Provides integration between users, applicationsand data


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Oracle9i : OORDBMS

User-Defined data types and objectsFully compatible with relational database

Support of multimedia and Large objects

It also support client server and web based applications

Oracle 9i can scale tens of thousands of concurrent users andsupport up to 512 petabytes of data ( A peta byte is 1000 terabytes)


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Environment

Oracle uses two types of Environments for executing our SQL

statements. SQL*plus and iSQL*plus.iSQL*plus is

An Environment

Oracle proprietaryKeywords can be abbreviated

Runs on a browser

Centrally loaded, does not have to be implemented on eachmachine


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Tools of Oracle

SQL * PLUS ISQLPLUS PL/SQL FORMS

REPORTS


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SQL commands

Data Definition Language (DDL) : CREATE, ALTER, DROP,

TRUNCATE

Data Manipulation Language (DML) : INSERT, UPDATE,DELETE

Transaction Control Language (TCL) : COMMIT, ROLLBACK,SAVEPOINT

Data Retrieval Language (DRL) : SELECT

Data Control Language (DCL) : GRANT, REVOKE

D t T


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Data Types

Data Type DescriptionVARCHAR2( size ) Variable-length character data

( 4000 bytes)

CHAR (size) Fixed-length character data up to2000 chars

NUMBER ( p , s) Variable-length numeric data

DATE Date and time values

LONG Variable-length character data upto 2GB

CLOB Character data up to 4 GBRAW and LONG RAW Raw binary data (Raw is 2000 bytes

and Long Raw is 4 GB)


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Data Types

BLOB Binary data up to 4 GB

BFILE Binary data stored in an external file up to4GB

NVARCHAR2(size) Variable-length character 4000 bytes/chars)depending upon National Character Set

TIMESTAMP (precision) Date plus time


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Writing Basic SQL SELECT Statements


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Basic SELECT Statement

SELECT *|{[DISTINCT] column | expression [ alias ],...}FROM table;

SELECT identifies what columns FROM identifies which table


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SELECT *FROM DEPT;

Selecting All Tables and Columns

SELECT *FROM TAB;

DESC[RIBE] DEPT

SELECT DEPTNO,LOCFROM DEPT;


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Writing SQL Statements

SQL statements are not case sensitive.

SQL statements can be on one or more lines.

Keywords cannot be abbreviated or split across lines.

Clauses are usually placed on separate lines.

Indents are used to enhance readability.


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Using Arithmetic Operators

SELECT ENAME, SAL, SAL + 300FROM EMP;


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Defining a Null Value

null is a value that is unavailable, unassigned, unknown, or inapplicable. A null is not the same as zero or a blank space.

SELECT ENAME, JOB, SAL, COMM FROM EMP;

Null Values


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SELECT ENAME, 12*SAL*COMM FROM EMP;

in Arithmetic Expressions

Arithmetic expressions containing a null value evaluate to null.


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Defining a Column Alias

A column alias: Renames a column heading

Is useful with calculations

follows the column name - there can also be the optional ASkeyword between the column name and alias

double quotation marks if it contains spaces or special charactersor is case sensitive

l l


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Using Column Aliases

SELECT EENAME "Name", SAL*12 "Annual Salary"FROM EMP;

SELECT ENAME AS name , COMM commissionFROM EMP;

C i O


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Concatenation Operator

A concatenation operator: Concatenates columns or character strings to other columns Is represented by two vertical bars (||) Creates a resultant column that is a character expression


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Using the Concatenation Operator

SELECT ENAME || JOB AS "Employees"

FROM EMP;

Lit l Ch t St i g


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Literal Character Strings

A literal is a character, a number, or a date included in theSELECT list.

Date and character literal values must be enclosed within singlequotation marks.

Each character string is output once for each row returned.

Using Literal Character Strings


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Using Literal Character Strings

SELECT ENAME ||' is a ' ||JOB

AS "Employee Details"FROM EMP;

Duplicate Rows


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Duplicate Rows

The default display of queries is all rows, including duplicate rows.

SELECT DEPTNOFROM EMP;

Eliminating Duplicate Rows


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Eliminating Duplicate Rows

Eliminate duplicate rows by using the DISTINCT keyword inthe SELECT clause.

SELECT DISTINCT DEPTNOFROM EMP;


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Restricting and Sorting Data

Objectives


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Objectives

After completing this lesson, you should be able to do the following: Limit the rows retrieved by a query

Sort the rows retrieved by a query

Limiting the Rows Selected


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Limiting the Rows Selected

Restrict the rows returned by using the WHERE clause.

The WHERE clause follows the FROM clause.

SELECT *|{[DISTINCT] column|expression [ alias ],...}FROM table[WHERE condition(s) ];

Using the WHERE Clause


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SELECT EMPNO, ENAME, JOB, DEPTNO

FROM EMP

WHERE DEPTNO = 30 ;

Character Strings and Dates


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Character Strings and Dates

Character strings and date values are enclosed in single quotationmarks. Character values are case sensitive, and date values are formatsensitive. The default date format is DD-MON-RR.

SELECT ENAME, JOB, DEPTNO

FROM EMP

WHERE ENAME = 'WARD';

Comparison Conditions


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Operator

=

>

>=

=10000

AND JOB LIKE '%MAN%';

Using the OR Operator


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OR requires either condition to be true.

SELECT EMPNO, ENAME, JOB, SAL

FROM EMP

WHERE SAL >= 10000

OR JOB LIKE '%MAN%';

Using the NOT Operator


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SELECT ENAME, JOB

FROM EMP

WHERE JOB

NOT IN (MANAGER', 'CLERK', 'SALESMAN');

Rules of Precedence


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Override rules of precedence by using parentheses.

Order Evaluated Operator1 Arithmetic operators2 Concatenation operator3 Comparison conditions

4 IS [NOT] NULL , LIKE , [NOT] IN5 [NOT] BETWEEN6 NOT logical condition7 AND logical condition8 OR logical condition

Rules of Precedence


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SELECT ENAME, JOB, SAL

FROM EMP

WHERE JOB = 'SALESMAN'

OR JOB = 'PRESIDENT'

AND SAL > 15000;

Rules of Precedence


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SELECT ENAME, JOB, SAL

FROM EMP

WHERE (JOB = 'SALESMAN'

OR JOB = 'PRESIDENT')

AND SAL > 15000;

Use parentheses to force priority .

ORDER BY Clause


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SELECT ENAME, JOB, DEPTNO, HIREDATE

FROM EMP

ORDER BY HIREDATE ;

Sort rows with the ORDER BY clause ASC: ascending order, default DESC: descending order

The ORDER BY clause comes last in the SELECT

statement.

Sorting in Descending Order


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SELECT ENAME, JOB, DEPTNO, HIREDATE

FROM EMP

ORDER BY HIREDATE DESC ;

Sorting by Column Alias


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SELECT EMPNO, ENAME, SAL*12 annsal

FROM EMP

ORDER BY annsal;

Sorting by Multiple Columns


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The order of ORDER BY list is the order of sort.

You can sort by a column that is not in theSELECT list.

SELECT EMPNO, DEPTNO, SAL

FROM EMP

ORDER BY DEPTNO, SAL DESC;

Summary


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SELECT *|{[DISTINCT] column|expression [ alias ],...}FROM table[WHERE condition(s) ][ORDER BY { column, expr, alias } [ASC|DESC]];

In this lesson, you should have learned how to:

Use the WHERE clause to restrict rows of output Use the comparison conditions Use the BETWEEN, IN, LIKE, and NULL conditions Apply the logical AND, OR, and NOT operators

Use the ORDER BY clause to sort rows of output

Exercise

1) Display the names with single word


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1) Display the names with single word 2) Display the names with two words 3) Display the names with exactly three words 4) Display all the salaries beginning with digit 2 5) Display all the names with second letter as A 6) Display the employees who joined between any two given

dates

7) Display the names and experience of all the employees 8) How many employees does not draw salary between 5000and 10000

9) Display all the names whose names contain underscore(_) 10)Calculate the experience in years for each employee and

display along with their names, in descending order.

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SQL Day1 Session1