1. Guide to Oracle 10g
Chapter 2:
Creating and Modifying
Database Tables

2. The Oracle 10g Client/Server Database
Latest release of Oracle Corporation’s relational database
Client/server database
Server side
DBMS server process
Oracle Net
Utility that enables network communication between client and server
Guide to Oracle 10g

3. Client/Server Architecture for Oracle 10g DBMS
Guide to Oracle 10g

4. The Oracle 10g Client/Server Database (continued)
Oracle Application Server
Used to create World Wide Web pages that allow users to access Oracle databases
Oracle client products:
SQL*Plus
Oracle 10g Developer Suite
Enterprise Manager
Guide to Oracle 10g

5. Database Objects An Oracle database consists of multiple user accounts
Each user account owns database objects
Tables
Views
Stored programs
Etc.

6. Database Queries
Query: command to perform operation on database object
Create
Modify
View
Delete
Structured Query Language (SQL)
Standard query language for relational databases

7. SQL Command Types Data Definition Language (DDL)
Used to create and modify the structure of database objects
Data Manipulation Language (DML)
Used to insert, update, delete, and view database data

8. DDL Commands
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

9. DML Commands Used to insert, view, and modify database data
UPDATE
DELETE
SELECT
DML commands need to be explicitly saved or rolled back
COMMIT
ROLLBACK

10. User Accounts Each Oracle database user has a user schema
Area in the database where the user’s database objects are stored
Identified by a unique username and protected by a password
Each user schema is granted specific privileges

11. Types of Database Privileges
System Privileges
Control the operations that the user can perform within the database
Connecting to the database (Create Session), creating new tables, shutting down the database, etc.
Object Privileges
Granted on individual database objects
Controls 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

12. Break Time: SQL Plus
Oracle SQL command line utility for issuing SQL commands
Starting SQL Plus
LOGON to YOUR Oracle Account

13. How to Access Your Oracle Account
1. Click the START button, point to Programs
2. Select Oracle –Oracle10g, then
3. Click Application Development, then
4. Select SQL PLUS
User Name:
Password:
Host string:

14. Creating New User Accounts
Done by DBA
Syntax:
CREATE USER username IDENTIFIED BY password;

15. Oracle Naming Standard
Oracle database objects must adhere to the Oracle Naming Standard
1 to 30 characters long
Must begin with a character
Can contain characters, numbers, and the symbols $, _, and #

16. Defining Database Tables
To create a table, you must specify:
Table name
Field names
Field data types
Field sizes
Constraints

17. Table and Field Names Must follow the Oracle Naming Standard
Each table in a user schema must have a unique name within that user schema
Each field in a table must have a unique name within that table

18. CREATE TABLE tablename
Creating a Table
CREATE TABLE tablename
(fieldname1 data_type,
(fieldname2 data_type, …)

19. Oracle Data Types Data type: specifies type of data stored in a field
Date, character, number.
LONG, RAW, LONG RAW, BLOB
Uses
Error checking
Efficient use of storage space

20. Oracle Character Data Types
VARCHAR2
columnname VARCHAR2(max_size)
Variable-length character strings
Max_size can be between 1 and 4,000 characters
Must specify the size
No trailing blank spaces are added
If more than max_size data is inserted, an error occurs.
Example declaration:
student_name VARCHAR2(30)

21. Character Data Types CHAR columnname CHAR(max_size)
Fixed-length character data
Max_size can be between 1 and 2000 characters
Max_size is optional. Default is 1.
Adds trailing blank spaces to pad width
If more than max_size data is inserted, an error occurs.
Example declaration:
student_gender CHAR(2)

22. Character Subtypes Examples: VARCHAR2(5) ‘Smith’ or ‘Smi’

23. Question: Which query will possibly generate student information?
s_last CHAR(15);
SELECT s_last, s_first, s_address
FROM student
WHERE s_last = ‘Smith’;
s_last VARCHAR2(15);
SELECT s_last, s_first, s_address
FROM student
WHERE s_last = ‘Smith’;
What data type should be used if there is any chance that all column spaces will NOT be filled?
Answer: VARCHAR2

24. Character Data Types 3. NVARCHAR2 and NCHAR
Analogous to VARCHAR2 and CHAR but use Unicode rather than ASCII
Used to hold character data in languages other than English (Japanese).

25. Number Data Type NUMBER General declaration format:
stores negative, positive, fixed, and floating point numbers values between and 10126
General declaration format:
variable_name NUMBER(precision, scale)

26. NUMBER Data Types
Number type (integer, fixed point, floating point) specified by precision and scale
Precision: total number of digits on either side of the decimal point. It does not include the decimal point itself or any commas or any formatting symbols.
Scale: number of digits to right of decimal point

27. Integer Numbers Whole number with no digits to right of decimal point
Precision is maximum width
Scale is omitted
Sample declaration:
s_age NUMBER (2)

28. 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)
(decimal point is not included)

29. Floating Point Numbers
Contain a variable number of decimal places
Precision and scale are omitted
Sample declaration:
s_GPA NUMBER

30. Date Data Type DATE Default date format: DD-MON-YY HH:MI:SS AM
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 HH:MI:SS AM
example: 05-JUN-03 12:00:00 AM
Sample declaration:
s_dob DATE

31. Specifying Date and Time Values
If no time value is given when a new date is inserted, default value is 12:00:00 AM
If no date value is given when a new time is inserted, default date is first day of current month

32. TIMESTAMP Data Type
The same as Date DT, but it stores also fractional seconds.
Field Timestamp(Fr_Se_Precision)
E.g: ship_dt Timestamp(2)
Fractional Seconds Precision default value is 6 (If omitted).

33. Interval Year to Month Data Type
Field Interval Year(Y_Pr) To Month.
Y_Pr: Year Precision(Default: 6).
E.g: elapsed Interval Year(2) To Month.
Possible Values:
:add 2 years and 11 months to a known date.
-11-4:subtract 11 years and 4 months.

34. Interval Day to Second Data Type
Field Interval Day(D_Pr) To Second(Fr_Se_pr).
D_Pr: Day Precision(Default : 2).
Fr_Se_Pr: Fractional Seconds Precision (Default : 6).
Possible value:
-04 03:20:32.00
(Days Hours:Minutes:Seconds.Fractions)

35. Examples
Source: java2s.com

36. Large Object (LOB) Data Types
Binary Large Object (BLOB)
Stores up to 4 GB of binary data
Character Large Object (CLOB)
Stores up to 4 GB of character data
BFILE
Stores a reference to a binary file maintained in the operating system
NCLOB
Character LOB that supports 16-bit character code

37. 6. Large Object (LOB) Data Types
Ex: f_image BLOB;

38. Declaring LOB Data Fields
Item size is not specified
Examples:
item_image BLOB
item_image BFILE

39. Creating a Database Table
Syntax:
CREATE TABLE table_name
( fieldname1 datatype,
fieldname2 datatype, …);
Example:
CREATE TABLE my_students
( s_id NUMBER(6),
s_name VARCHAR2(30),
s_dob DATE,
s_class CHAR(2));

40. Constraints
Rules that restrict the values that can be inserted into a field
Types of constraints
Integrity: define primary and foreign keys
Value: specify values or ranges of values that can be inserted

41. Constraint Levels Table constraint Column constraint
Restricts the value of a field with respect to all other table records
Example: primary key value must be unique for each record
Column constraint
Restricts values in a specific column
Example: values in an S_GENDER field must be ‘M’ or ‘F’

42. Constraint Names Internal name used by DBMS to identify the constraint
Each constraint name in a user schema must be unique
If you do not name a constraint, the system will automatically generate an unintuitive name

43. Constraint Names Constraint naming convention: Constraint ID values:
tablename_fieldname_constraintID
Constraint ID values:
Primary key: pk
Foreign key: fk
Check condition: cc
Not NULL: nn
Unique: uk
Example constraint name:
my_students_s_id_pk

44. Primary Key Constraints
Table-level
Defining a primary key:
CONSTRAINT constraint_name PRIMARY KEY
Example:
s_id NUMBER(6)
CONSTRAINT student_s_id_pk PRIMARY KEY

45. Primary Key Constraints
Can be defined when field is declared

46. Primary Key Constraints
Can also be defined after all table field definitions are completed

47. Composite Primary Keys
Syntax:
CONSTRAINT constraint_name
PRIMARY KEY (field1, field2)
Must be defined after fields that compose key are defined

48. Foreign Key Constraints
Table-level
Can only be defined after field is defined as a primary key in another table
Syntax:
CONSTRAINT constraint_name
REFERENCES primary_key_table_name (field_name)

49. Foreign Key Constraints
Can be defined when field is declared

50. Foreign Key Constraints
Can also be defined after all table field definitions are completed

51. Value Constraints Column-level
Restricts data values that can be inserted in a field
In general, avoid value constraints because they make the database very inflexible

52. Types of Value Constraints
Check condition: restricts to specific values
Example: s_gender (M or F)
CONSTRAINT my_students_s_gender_cc
CHECK (s_gender = ‘M’) OR (s_gender = ‘F’)
Not NULL: specifies that a field cannot be NULL
Example:
CONSTRAINT my_students_s_dob_nn
NOT NULL

53. Types of Value Constraints
Default: specifies a default value that is inserted automatically
Example:
s_state CHAR(2) DEFAULT ‘WI’
Unique
Table constraint
Specifies that a non-primary key field must have a unique value
CONSTRAINT consultant_c_ _uk UNIQUE (c_ )

54. SQL*Plus Oracle SQL command line utility for issuing SQL commands
Starting SQL*Plus

55. Using SQL*Plus All commands must be terminated with a semicolon
Use a text editor and copy and paste commands
Character data is case sensitive and must be in single quotes
‘M’
‘Sarah’

56. Exiting SQL*Plus Type exit at SQL> promptor
Click Close button on SQL*Plus window

57. Oracle Help Resources Ora.hlp file Oracle Technology Network (OTN)

58. Viewing Table Information
Viewing a table’s structure
DESCRIBE table_name;

59. Oracle Data Dictionary
Contains tables that describe the database structure
Is in the SYSTEM user schema
Is automatically updated as users create and modify tables
Cannot be updated directly
Contains views that allow users to retrieve information about the database structure

60. Data Dictionary Views
Views present data in different formats depending on the privileges of the user
USER: shows all objects belonging to the current user
ALL: shows all objects belonging to the current user, as well as objects current user has privileges to manipulate
DBA: allows users with DBA privileges to view objects of all database users

61. Querying the Data Dictionary Views
Syntax:
SELECT field1, field2, …
FROM privilege_viewname;

62. Summary of Oracle Data Dictionary Views
OBJECTS
All database objects
TABLES
Database tables
INDEXES
Table indexes created to improve query performance
VIEWS
Database views
SEQUENCES
Sequences created to automatically generate surrogate key values
USERS
Database users
CONSTRAINTS
Table constraints
CONS_CONSTRAINTS
Table columns that have constraints
IND_COLUMNS
Indexed columns
TAB_COLUMNS
All table columns

63. Modifying Tables Unrestricted actions Renaming tables
GF: Rename Old_tableName To new_tableName; Ex
Rename Faculty To New_Faculty

64. Modifying Tables ALTER TABLE T_name Action Rename Add Modify Drop
E / D
F_old_name To
F_new_name
(Field_name
DataType
[Constraint])
(Field_name
TYPE )
Column
Field_name
Enable
Const_name
Constraint
Const_name
Disable
Const_name
Constraint
Cons_specif
New_one
Increase_size
Decrease_size

65. Modifying Tables Unrestricted actions Adding new columns
GF: ALTER TABLE table_name ADD (Field Data type Constraint);
Ex: ALTER Table Faculty Add (Start_date date);

66. Modifying Tables Unrestricted actions Increasing column sizes
ALTER TABLE table_name MODIFY (column new_datType);
Dropping columns
ALTER TABLE table_name DROP COLUMN column_name;
Dropping constraints
ALTER TABLE table_name DROP COSRAINT constraint_name;

67. Modifying Tables Restricted actions Dropping tables
Only allowed if table does not contain any fields that are referenced as foreign keys, or if foreign key constraints are dropped
Changing a column’s data specification
Only allowed if existing data is compatible with new data specification
Decreasing column sizes
Only allowed if column does not contain any data
Adding constraints
Only allowed if existing data meets requirements of new constraint

68. Altering Tables Adding a new field: ALTER TABLE tablename
ADD (fieldname field_specification);

69. Altering Tables Modifying an existing field: ALTER TABLE tablename
MODIFY (fieldname new_field_specification);

70. Altering Tables Deleting an existing field: ALTER TABLE tablename
DROP COLUMN fieldname;

71. Altering Tables Enabling and Disabling Constraints:
ALTER TABLE tablename
Enable|Disable CONSTRAINT constraint_name;
E.g: Alter Table faculty
Disable Constraint faculty_f_id_fk;

72. Deleting Tables
Syntax to delete table if no table fields are referenced as foreign keys:
DROP TABLE tablename;
Syntax to delete table and constraints if table contains fields that are referenced as foreign keys:
DROP TABLE tablename CASCADE CONSTRAINTS;

73. DROP: CASCADE CONSTRAINTS
Dropping the table that has the primary key which is used as a foreign key in another table (using CASCADE CONSTRAINTS) will keep the values of that foreign key of the importing table.
However, there is no reference at this point