Oracle 10g

Oracle Database
for Developers
Introduction to Oracle, SQL
Developer, SQL, PL/SQL, …
Svetlin Nakov
Technical Trainer
www.nakov.com
Software University
http://softuni.bg

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 This lesson is NOT for absolute beginners
 Target audience:
 Familiar with databases (MySQL / SQL Server / other)
 Know what is table / column / relationship
 Know what is SQL and simple SQL commands
 Have basic coding skills (C# / Java / JS / other)
Target Audience

Table of Contents
1. Oracle Database Overview
2. Installing Oracle Database 12c
3. Installing SQL Developer
4. Creating DB Schemas and Tables
5. SQL Language Basics
 SELECT, INSERT, UPDATE, DELETE, …
6. PL/SQL: Procedures, Functions, Triggers
7. Accessing Oracle from C# and Java
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 Oracle Database
 World's leader in enterprise database systems
 Powers big organizations, e.g. the financial sector
 Designed for very large databases (exabytes of data)
 Supports everything from the DB world
 Transactions, stored procedures, big data, cloud, …
 Very expensive, for big players only
 Has a free Expression Edition – Oracle 11g XE
What is Oracle Database?

Installing Oracle 12c / 11g XE

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Installing Oracle 12c
Typically, Oracle 12c
DB Enterprise takes
~ 10GB HDD space

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Installing Oracle 12c – Use a Built-In User
Developers may use
"Windows Built-in Account"
for simplified setup

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Installing Oracle 12c – Location & Password
Select a directory
without spaces,
e.g. C:oracle
Don't select "Container
database". It is too complex!

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Installing Oracle 12c – Be Patient 
Usually it takes
20-30 minutes

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 Oracle DB Express Edition (XE)
 Free, limited, lightweight version
 1 CPU, 1 GB RAM, 11 GB storage
 Only 11g (no 12c version)
 Installing Oracle Database XE
 Download Oracle Database XE 11g
 Install it in a folder without spaces, e.g. C:Progra~1Oracle
 Remember the admin password (for the users SYS and SYSTEM)
Alternative: Oracle Express Edition (XE)
Use Oracle XE
for slower
computers

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 OracleServiceORCL / OracleServiceXE
 The Oracle database engine for the "ORCL" / "XE" instance (SID)
 The core of the Oracle database
 OracleOraDB12Home1TNSListener / OracleXETNSListener
 Connects Oracle database with client applications (TNS service)
 Listens on TCP port 1521 (TNS listener)
 Enterprise Manager (EM) console – https://localhost:5500/em
 Application Express Web interface (APEX) – http://localhost:8080
Oracle Database Services and Ports

Install Oracle 12c Database
Live Exercise in Class (Lab)

Oracle SQL Developer
Installing and Using SQL Developer

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 Oracle SQL Developer is free GUI tool for managing Oracle databases:
SQL queries, edit table data, edit DB schema, write code, debug, …
Oracle SQL Developer
Oracle 12c Enterprise comes with
pre-installed SQL Developer 3.2
(old version, not recommended)

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1. Download Oracle SQL Developer 4.1 from
http://oracle.com/technetwork/developer-tools/sql-developer
2. Extract the ZIP archive in some folder, e.g.
C:oraclesqldeveloper
3. Run sqldeveloper.exe
4. Choose your JDK location
5. Create a start menu shortcut
6. Enjoy 
Installing Oracle SQL Developer

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Connecting to Oracle with SQL Developer
Use "ORCL" or "XE"
as SID (System ID)

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 User SYS
 Holds the system schema SYS and data dictionary (DB metadata)
 Has a DBA role
 Includes most database system privileges, e.g. "create user"
 Has a SYSDBA privilege – can start / stop / create / recover DB
 User SYSTEM
 Has a DBA role – can administer the DB, e.g. create / drop users
 No SYSDBA privilege
Users SYS and SYSTEM in Oracle DB

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Unlocking the "HR" User (Schema)

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Connecting with the "HR" User

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View / Edit Data in the "HR" Shema

Install Oracle SQL Developer
and Access the "HR" Schema

Creating DB Schemas and Tables
Creating Users, Tables, Relationships, Etc.

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 Oracle runs single database with multiple users
 MS SQL Server and MySQL have many databases
 "User (schema) in Oracle" == "Database" in MSSQL and MySQL
 Creating a new user (schema) and give typical privileges:
Creating a New User (Schema) in Oracle
CREATE USER maria IDENTIFIED BY "password123";
GRANT CREATE SESSION, CREATE TABLE, CREATE VIEW,
CREATE PROCEDURE, CREATE SEQUENCE, CREATE TRIGGER,
UNLIMITED TABLESPACE TO maria;

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 Users in Oracle may have certain privileges
 CREATE SESSION – allows the users to connect to DB
 CREATE TABLE / CREATE VIEW / CREATE PROCEDURE / …
 UNLIMITED TABLESPACE – unlimited storage quota (0 by default)
 SYSDBA – start / stop / edit / backup the entire database
 Users in Oracle may have certain roles
 DBA – database administrator (full DB access)
 CONNECT + RESOURCE – login + create / edit tables and DB objects
User Privileges and Roles in Oracle

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Creating a New User in SQL Developer
Granting "DBA" role
is easy but might be
a security risk

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Creating Tables in SQL Developer: COUNTRIES

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 NUMBER(precision, scale) – a number, e.g. 12345
 precision – total number of digits
 scale – number of digits to the right of the decimal point
 VARCHAR2(length) – sequence of characters (up to 4000)
 NVARCHAR2(length) – sequence of Unicode characters
 DATE – date and time, e.g. "18-June-2015 20:30:07"
 BLOB – binary large object (e.g. PDF document or JPEG image)
 CLOB – character large object (e.g. HTML document)
Oracle Data Types

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 Oracle database has some specifics
 One database with many users (schemas)
 Each user has its own schema (tables and other DB objects)
 Use UPPERCASE for all identifiers
 Otherwise you should use the quoted syntax, e.g. "My Table"
 No auto-increment columns until version 12c
 Use a SEQUENCE + TRIGGER for auto-increment in Oracle 11g / 10g
 In Oracle NULL is the same like "" (empty string)
 This causes many problems!
Beware: Oracle has Specifics!

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Editing Table Data in SQL Developer

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Creating Tables in SQL Developer: TOWNS

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Creating Relationships in SQL Developer
First save the "TOWNS"
table, then edit it to add
the foreign key constraint

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Foreign Key Constraint Violation

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Creating E/R Diagram with Data Modeler

Creating DB Schema "Maria" Holding
Countries and Towns (One to Many)

SQL Language – Basics
Basics SQL Commands: SELECT, INSERT,
UPDATE, DELETE, CREATE, ALTER, DROP
SELECT *
FROM COUNTRIES
WHERE COUNTRY_ID = 'UK'
SELECT
c.COUNTRY_NAME AS COUNTRY,
r.REGION_NAME AS REGION
FROM COUNTRIES c
JOIN REGIONS r ON
c.REGION_ID = r.REGION_ID

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 SELECT
 WHERE (filtering)
 JOIN (joining tables)
 GROUP BY (grouping)
 INSERT
 UPDATE
 DELETE
SQL Language
SELECT
d.DEPARTMENT_NAME AS DEPT,
COUNT(e.EMPLOYEE_ID) AS EMP_COUNT
FROM
DEPARTMENTS d JOIN EMPLOYEES e ON
e.DEPARTMENT_ID = d.DEPARTMENT_ID
GROUP BY
d.DEPARTMENT_ID, d.DEPARTMENT_NAME
HAVING
COUNT(e.EMPLOYEE_ID) >= 5
ORDER BY
EMP_COUNT DESC

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 In Oracle, we have the "HR" schema, coming as example
 The "HR" schema holds:
 Employees
 Jobs
 Departments
 Locations (addresses)
 Countries
 To use it, unlock the "HR" user and change its password
The HR Sample Schema

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 SELECT
 WHERE
 ORDER BY
SQL: SELECT, WHERE, ORDER BY
SELECT * FROM COUNTRIES
SELECT COUNTRY_ID, REGION_ID
FROM COUNTRIES
WHERE COUNTRY_ID = 'UK'
WHERE COUNTRY_ID LIKE 'C%'
OR COUNTRY_NAME LIKE 'Un%'
ORDER BY COUNTRY_NAME
ORDER BY COUNTRY_ID DESC
FETCH NEXT 3 ROWS ONLY

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 Join COUNTRIES with REGIONS tables in SQL SELECT
SQL: Join Tables
SELECT *
FROM COUNTRIES JOIN REGIONS
ON COUNTRIES.REGION_ID =
REGIONS.REGION_ID
SELECT c.COUNTRY_NAME AS COUNTRY,
r.REGION_NAME AS REGION
FROM COUNTRIES c JOIN REGIONS r
ON c.REGION_ID = r.REGION_ID

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 Insert a new department
SQL: INSERT
INSERT INTO DEPARTMENTS(
DEPARTMENT_ID,
DEPARTMENT_NAME,
LOCATION_ID)
VALUES (
DEPARTMENTS_SEQ.nextval,
'Brazil Sales',
2800 /* Sao Paulo, Brazil */)
Primary key is
populated by a
SEQUENCE

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 Update existing department  change name + commit
 Update existing employee  change hire date + rollback
SQL: UPDATE
UPDATE EMPLOYEES SET HIRE_DATE = '2-Jan-2001'
WHERE EXTRACT(YEAR FROM HIRE_DATE) = 2001;
ROLLBACK; -- Discard (cancel) pending changes
UPDATE DEPARTMENTS
SET DEPARTMENT_NAME = 'Brazil Sales and Marketing'
WHERE DEPARTMENT_NAME = 'Brazil Sales'
COMMIT; -- Save pending changes

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 Delete existing department + commit
 Delete all locations in Italy + rollback
SQL: DELETE
DELETE FROM DEPARTMENTS
WHERE DEPARTMENT_ID = 320;
COMMIT; -- Save pending changes
DELETE FROM LOCATIONS
WHERE COUNTRY_ID =
(SELECT COUNTRY_ID FROM COUNTRIES
WHERE COUNTRY_NAME = 'Italy');
ROLLBACK; -- Discard (cancel) pending changes

SQL Commands
Live Exercise (Lab)
1. Write SQL SELECT to find all locations in towns starting with 'S'.
2. Write SQL INSERT to create a new job (id 'SW_DEV', title 'Software
Developer', salary range 10000 … 50000).
3. Write SQL UPDATE to change the job title 'Software Developer' to
'Software Engineer' and max salary to 75000.
4. Write SQL DELETE to remove the job title 'Software Engineer'.
5. Write a SQL SELECT to find all job titles and the number of
employees for each job title. Use GROUP BY JOB_ID.
More exercises: http://www.srikanthtechnologies.com/oracle/dec9/hrqueries.html

The PL/SQL Language
Programming Logic in the Database

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 PL/SQL extends the SQL language in Oracle DB
 Blocks (declare / begin / exception / end)
 Variables, types, assignments
 Conditional statements (if-then-else)
 Loops (for, while, do…while)
 Cursors (loops over query results)
 Exceptions handling
 Stored procedures, functions, triggers, packages
PL/SQL Overview

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PL/SQL – Example
SET SERVEROUTPUT ON
DECLARE
e_id EMPLOYEES.EMPLOYEE_ID%TYPE;
e_fname EMPLOYEES.FIRST_NAME%TYPE;
e_lname EMPLOYEES.LAST_NAME%TYPE;
CURSOR e_employees IS
SELECT EMPLOYEE_ID, FIRST_NAME, LAST_NAME
FROM EMPLOYEES;
result CLOB;
BEGIN
result := NULL;
OPEN e_employees;
Goal of this PL/SQL program:
Collect the employee data into a
single string (comma separated)

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PL/SQL – Example (2)
LOOP
FETCH e_employees INTO e_id, e_fname, e_lname;
EXIT WHEN e_employees%NOTFOUND;
IF result IS NOT NULL THEN
result := result || ', ';
END IF;
result := result || e_id || ' (' ||
e_fname || ' ' || e_lname || ')';
END LOOP;
CLOSE e_employees;
DBMS_OUTPUT.PUT_LINE(result);
END;

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PL/SQL: Interchange Salaries – Example
CREATE OR REPLACE PROCEDURE exchange_salaries(
emp1_id NUMBER, emp2_id NUMBER)
IS
old_emp1_salary EMPLOYEES.SALARY%TYPE;
BEGIN
SELECT SALARY INTO old_emp1_salary
FROM EMPLOYEES WHERE EMPLOYEE_ID = emp1_id;
UPDATE EMPLOYEES SET SALARY =
(SELECT SALARY FROM EMPLOYEES WHERE EMPLOYEE_ID = emp2_id)
WHERE employee_id = emp1_id;
UPDATE EMPLOYEES SET SALARY = old_emp1_salary
WHERE EMPLOYEE_ID = emp2_id;
COMMIT;
END; CALL exchange_salaries(204, 206);

Accessing Oracle DB from Java
Using the Oracle JDBC Driver
Connection
Statement
ResultSet
Oracle DB
setInt(…)
setDate(…)
setString(…)

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Setup a Maven-Based Java Project
<project …>
<build>
<plugins>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<source>1.8</source>
<target>1.8</target>
</configuration>
</plugin>
</plugins>
</build>
</project>
pom.xml
Create a Maven project and
specify Java 8 compilation mode
(by default Maven uses Java 5)

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Reference the Oracle JDBC Drivers Library
<repositories>

<repository> <id>codelds</id>
<url>https://code.lds.org/nexus/content/groups/main-repo</url>
</repository>
</repositories>
<dependencies>
<dependency>
<groupId>com.oracle</groupId>
<artifactId>ojdbc7</artifactId>
<version>12.1.0.2</version>
</dependency>
</dependencies>
pom.xml
Add an unofficial Maven repository
holding the Oracle JDBC drivers
Reference the latest OJDBC
library (12.1 for Java 7+)

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List All Employees from the HR Schema
public static void main(String[] args) throws Exception {
Class.forName("oracle.jdbc.driver.OracleDriver");
try (Connection dbConnection = DriverManager.getConnection(
"jdbc:oracle:thin:@localhost:1521:orcl", "hr", "hr")) {
Statement stmp = dbConnection.createStatement();
ResultSet rs = stmp.executeQuery("SELECT * FROM EMPLOYEES");
while (rs.next()) {
int id = rs.getInt("EMPLOYEE_ID");
String firstName = rs.getString("FIRST_NAME");
String lastName = rs.getString("LAST_NAME");
System.out.println(id + ": " + firstName + " " + lastName);
}
}
}

Accessing Oracle DB from C#
Using the Oracle Data Provider for .NET
OracleConnection
OracleCommand
OracleDataReader
Oracle DB
OracleParameter
OracleParameter
OracleParameter

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Reference the Oracle Data Provider from NuGet

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Configure the Data Source in App.config
<oracle.manageddataaccess.client>
<version number="*">
<dataSource alias="orcl" descriptor=
"(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)
(HOST=localhost)(PORT=1521))
(CONNECT_DATA=(SERVICE_NAME=ORCL))) "/>
</version>
</oracle.manageddataaccess.client>
App.config

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List All Employees from the HR Schema
using (var dbCon = new OracleConnection(
"Data Source=orcl; User Id=hr; Password=hr"))
{
dbCon.Open();
var cmd = new OracleCommand("SELECT * FROM EMPLOYEES", dbCon);
var reader = cmd.ExecuteReader();
while (reader.Read())
{
int id = (int) reader["EMPLOYEE_ID"];
string firstName = (string) reader["FIRST_NAME"];
string lastName = (string) reader["LAST_NAME"];
Console.WriteLine(id + ": " + firstName + " " + lastName);
}
}

Accessing Oracle from Java and C#
Live Exercise (Lab)

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 Oracle is world's leading RDBMS
 Powerful, but complex
 Oracle SQL Developer
 DB GUI tool for developers
 SQL language
 SELECT, INSERT, UPDATE, DELETE
 PL/SQL – variables, conditions, loops, cursors, …
 Accessing from Java – use the Oracle JDBC drivers
 Accessing from C# – use the .NET Data Provider for Oracle
Summary

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Oracle Database for Developers
https://softuni.bg/courses/software-technologies

License
 This course (slides, examples, demos, videos, homework, etc.)
is licensed under the "Creative Commons Attribution-
NonCommercial-ShareAlike 4.0 International" license
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Oracle 10g

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