1. Guide to Oracle 10g1 Chapter 2: Creating and Modifying Database Tables

2. Guide to Oracle 10g2 Database Objects An Oracle database consists of multiple user accounts Each user account owns database objects Tables Views Stored programs Etc.

3. Guide to Oracle 10g3  Query: command to perform operation on database object  Create  Modify  View  Delete  Structured Query Language (SQL)  Standard query language for relational databases Database Queries

4. Guide to Oracle 10g4 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

5. Guide to Oracle 10g5 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

6. Guide to Oracle 10g6 DML Commands Used to insert, view, and modify database data INSERT UPDATE DELETE SELECT DML commands need to be explicitly saved or rolled back COMMIT ROLLBACK

7. Guide to Oracle 10g7 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

8. Guide to Oracle 10g8 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

9. Guide to Oracle 10g9  Oracle SQL command line utility for issuing SQL commands  Starting SQL Plus Break Time: SQL Plus LOGON to YOUR Oracle Account

10. Guide to Oracle 10g10 How to Access Your Oracle Account User Name: Password: Host string: 1. Click the START button, point to Programs 2. Select Oracle –Oracle10g, then 3. Click Application Development, then 4. Select SQL PLUS

11. Guide to Oracle 10g11 Creating New User Accounts Done by DBA Syntax: CREATE username IDENTIFIED BY password;

12. Guide to Oracle 10g12 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 #

13. Guide to Oracle 10g13  To create a table, you must specify:  Table name  Field names  Field data types  Field sizes  Constraints Defining Database Tables

14. Guide to Oracle 10g14  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 Table and Field Names

15. Guide to Oracle 10g15 Creating a Table CREATE TABLE tablename (fieldname1 data_type, (fieldname2 data_type, …)

16. Guide to Oracle 10g16  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 Oracle Data Types

17. Guide to Oracle 10g17  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) Oracle Character Data Types

18. Guide to Oracle 10g18  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) Character Data Types

19. Guide to Oracle 10g19 Character Subtypes Examples: VARCHAR2(5)‘Smith’ or ‘Smi’ CHAR(5)‘Smith’ or ‘Smi ’

20. Guide to Oracle 10g20 Question: Which query will possibly generate student information? What data type should be used if there is any chance that all column spaces will NOT be filled? Answer: VARCHAR2 s_last VARCHAR2(15); SELECT s_last, s_first, s_address FROM student WHERE s_last = ‘Smith’; s_last CHAR(15); SELECT s_last, s_first, s_address FROM student WHERE s_last = ‘Smith’;

21. Guide to Oracle 10g21 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). Character Data Types

22. Guide to Oracle 10g22  NUMBER  stores negative, positive, fixed, and floating point numbers values between 10 -130 and 10 126  General declaration format: variable_name NUMBER(precision, scale) Number Data Type

23. Guide to Oracle 10g23  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 NUMBER Data Types

24. Guide to Oracle 10g24  Whole number with no digits to right of decimal point  Precision is maximum width  Scale is omitted  Sample declaration: s_age NUMBER (2) Integer Numbers

25. Guide to Oracle 10g25  Contain a specific number of decimal places  Precision is maximum width  Scale is number of decimal places  Sample declaration: item_price NUMBER(5, 2) 259.99 33.89 (decimal point is not included) Fixed Point Numbers

26. Guide to Oracle 10g26  Contain a variable number of decimal places  Precision and scale are omitted  Sample declaration: s_GPA NUMBER Floating Point Numbers

27. Guide to Oracle 10g27  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 HH:MI:SS AM  example: 05-JUN-03 12:00:00 AM  Sample declaration: s_dob DATE Date Data Type

28. Guide to Oracle 10g28  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 Specifying Date and Time Values

29. Guide to Oracle 10g29  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). TIMESTAMP Data Type

30. Guide to Oracle 10g30  Field Interval Year(Y_Pr) To Month.  Y_Pr: Year Precision(Default: 6).  E.g: elapsed Interval Year(2) To Month.  Possible Values: +02-11 :add 2 years and 11 months to a known date. -11-4:subtract 11 years and 4 months. Interval Year to Month Data Type

31. Guide to Oracle 10g31  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) Interval Day to Second Data Type

32. Guide to Oracle 10g32 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

33. Guide to Oracle 10g33 6. Large Object (LOB) Data Types Ex: f_image BLOB;

34. Guide to Oracle 10g34 Declaring LOB Data Fields Item size is not specified Examples: item_image BLOB item_image BFILE

35. Guide to Oracle 10g35  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)); Creating a Database Table

36. Guide to Oracle 10g36 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

37. Guide to Oracle 10g37 Constraint Levels Table 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’

38. Guide to Oracle 10g38  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 starts with SYS_Cn. n is a numeric value. Constraint Names

39. Guide to Oracle 10g39  Constraint naming convention: 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 Constraint Names

40. Guide to Oracle 10g40 Constraint Names 10g too

41. Guide to Oracle 10g41  Table-level  Defining a primary key: CONSTRAINT constraint_name PRIMARY KEY  Example: s_id NUMBER(6) CONSTRAINT student_s_id_pk PRIMARY KEY Primary Key Constraints

42. Guide to Oracle 10g42  Can be defined when field is declared Primary Key Constraints

43. Guide to Oracle 10g43  Can also be defined after all table field definitions are completed Primary Key Constraints

44. Guide to Oracle 10g44  Syntax: CONSTRAINT constraint_name PRIMARY KEY (field1, field2)  Must be defined after fields that compose key are defined Composite Primary Keys

45. Guide to Oracle 10g45  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) Foreign Key Constraints

46. Guide to Oracle 10g46  Can be defined when field is declared Foreign Key Constraints NOTE: faculty TABLE MUST EXIST BEFORE my_students.

47. Guide to Oracle 10g47  Can also be defined after all table field definitions are completed Foreign Key Constraints

48. Guide to Oracle 10g48  Column-level  Restricts data values that can be inserted in a field  In general, avoid value constraints because they make the database very inflexible Value Constraints

49. Guide to Oracle 10g49  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 Types of Value Constraints

50. Guide to Oracle 10g50  Default: specifies a default value that is inserted automatically unless the user insert an other value  Example: Must be created in the column declaration, NOT a separate command beginning with CONSTRAINT. s_state CHAR(2) DEFAULT ‘WI’  Unique  Table constraint  Specifies that a non-primary key field must have a unique value CONSTRAINT consultant_c_email_uk UNIQUE (c_email) (Primary key constrain does not allow NULL, but this does) Types of Value Constraints

51. Guide to Oracle 10g51  Oracle SQL command line utility for issuing SQL commands  Starting SQL*Plus SQL*Plus

52. Guide to Oracle 10g52  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’  Commands are NOT case sensitive. Using SQL*Plus

53. Guide to Oracle 10g53  Type exit at SQL> prompt or  Click Close button on SQL*Plus window Exiting SQL*Plus

54. Guide to Oracle 10g54  Ora.hlp file  Oracle Technology Network (OTN)  http://otn.oracle.com Oracle Help Resources

55. Guide to Oracle 10g55 Create a Table

56. Guide to Oracle 10g56 Using Notepad Useful to use Notepad to edit sql commands Commands can be edited without retyping Commands can be saved Saving multiple sql commands in a file creates a script

57. Guide to Oracle 10g57 Study … Can you create TABLE student now?

58. Guide to Oracle 10g58 Table Creation Sequence When creating tables with foreign key references, create referenced tables first Always create tables without foreign keys before those with foreign keys

59. Guide to Oracle 10g59  Viewing a table’s structure DESCRIBE table_name; Viewing Table Information

60. Guide to Oracle 10g60 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 View: is a db object that the DBMS bases on an actual db table and which enables the DBMS to present the table data in a different format based on user needs. It can serve to hide some table columns in which the user has no interest or doesn’t have privileges to view.

61. Guide to Oracle 10g61 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

62. Guide to Oracle 10g62 Querying the Data Dictionary Views Syntax: SELECT view_columnname1, view_columnname2, … FROM prefix_object; Try: DESCRIBE user_tables; to see the details of that table.

63. Guide to Oracle 10g63 Viewing Information About Tables General command: SELECT view_columnname1, view_columnname2, … FROM prefix_object; view_columnname1, view_columnname2,… are the name of the fields you want to retrieve from the view. prefix: either USER, ALL or DBA. object: the type of the DB object you are examining. See next slide for these objects. Ex: select table_name from user_tables; Table_name is a field name in the table user_tables. User_tables is a table saves the names of all the table you (user) create.

64. Guide to Oracle 10g64 Database Objects with Data Dictionary View Object NameObject Type OBJECTSAll database objects TABLESDatabase tables INDEXESTable indexes created to improve query performance VIEWSDatabase views SEQUENCESSequences created to automatically generate surrogate key values USERSDatabase users CONSTRAINTSTable constraints CONS_COLUMNSTable columns that have constraints IND_COLUMNSIndexed columns TAB_COLUMNSAll table columns

65. Guide to Oracle 10g65 Viewing Constraints on One Table Try: DESCRIBE user_constraints; to see the details of that table.

66. Guide to Oracle 10g66  Unrestricted actions: some specifications can always be modified.  Renaming tables  Adding new columns  Increasing column sizes  Dropping columns  Dropping constraints Modifying Tables

67. Guide to Oracle 10g67  Restricted actions: specifications modified only in certain situations  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 Modifying Tables

68. Guide to Oracle 10g68 Deleting and Renaming Tables To delete: DROP TABLE [tablename] Use with caution. It is a restricted actions, can not be dropped if it contains a foreign key. Delete the constraint and then drop the table or use cascade. To delete foreign key constraints, add “CASCADE CONSTRAINTS” To rename: RENAME old_tablename TO new_tablename DBMS automatically transfers to the new table integrity constraints, indexes, and privileges that referenced the old table. Views and stored program units that reference the old table name become Invalid.

69. Guide to Oracle 10g69 Altering Tables Adding a new field: ALTER TABLE tablename ADD (fieldname field_specification);

70. Guide to Oracle 10g70 Altering Tables Modifying an existing field: ALTER TABLE tablename MODIFY (fieldname new_field_specification); Can only change data type to compatible data type (i.e. varchar2 to char)

71. Guide to Oracle 10g71 Altering Tables Deleting an existing field: ALTER TABLE tablename DROP COLUMN fieldname; ALTER TABLE faculty ADD (faculty_rank VARCHAR2(4));

72. Guide to Oracle 10g72 Renaming a Column To rename a field ALTER TABLE tablename RENAME COLUMN old_fieldname TO new_fieldname; Ex: ALTER TABLE faculty RENAME COLUMN faculty_rank to f_rank;

73. Guide to Oracle 10g73 Adding and Deleting Constraints Add a constraint: ALTER TABLE tablename ADD CONSTRAINT constraint_name constraint_definition; Remove a constraint: ALTER TABLE tablename DROP CONSTRAINT constraint_name; Examples: ALTER TABLE faculty ADD CONSTRAINT faculty_f_pin_uk UNIQUE (f_pin); ALTER TABLE faculty DROP CONSTRAINT faculty_f_pin_uk;

74. Guide to Oracle 10g74 Enabling and Disabling Constraints When modifying a database it can be useful to disable constraints Constraints are enabled by default To disable a constraint: ALTER TABLE tablename DISABLE CONSTRAINT constraint_name; To enable a constraint: ALTER TABLE tablename ENABLE CONSTRAINT constraint_name; 1.ALTER TABLE faculty DISABLE CONSTRAINT faculty_loc_id_fk; 2.ALTER TABLE faculty ENABLE CONSTRAINT faculty_loc_id_fk; 3.DROP TABLE faculty CASCADE CONSTRAINTS; 4.EXIT;

75. Guide to Oracle 10g75 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;

76. Guide to Oracle 10g76 Summary SQL commands include: Data description language (DDL) commands: create, modify, Deleted database objects Data manipulation language (DML) commands: insert, update, delete, view database data To create a table: specify the table name, the name of each data field, and the data type and size of each data field Data types ensure correct data values Constraints restrict values of database fields SQL*Plus commands are not case sensitive

77. Guide to Oracle 10g77 Summary (cont.) Errors include line number, position, error code Use DESCRIBE command to display a table’s fieldnames and data types Tables can be modified or deleted but some changes are restricted

78. Guide to Oracle 10g78 End Of Chapter 2