Chapter Six Objectives Introduction to SQL Types of SQL statements Concepts of DDL & DML Creating Tables Restrictions on Tables Data Definition Language(DDL) Data Manipulation Language (DML)

2 SQL Structured Query Language Developed by IBM Used in most Commercial DBMS Statements are not case sensitive. Statements can be on one or more lines. Reserved words cannot be abbreviated or split over lines. Terminated with a semi colon. Statements are entered at SQL prompt. The subsequent lines are numbered (SQL buffer) Only one statement can be current at any time in the buffer.

3 Data Definition Language (DDL) Data Manipulation Language (DML) Transaction Control Session Control System Control Embedded SQL Types of SQL Statements

4 Example : Student(Name, ID, GPA, Major, B_Date) Course(C_Num, Dept, Title, Cr) Student_Course(ID, C_Num, Dept, Grade) Faculty(ID, Name, Dept, Salary, Area) Faculty_Course(ID, C_Num, Dept, Semester) Department(Name, Num_Faculty)

5 Data Definition Language (DDL) Format: CREATE TABLE[schima.]Table_Name (AttributeAttribute_Type [DEFAULT expr] [Col_constraint], …. AttributeAttribute_Type [Table_constraint]);

6 Data Definition Language (DDL) Example: SQL> CREATE TABLE student 2(NameVARCHAR2(80), 3IDNUMBER(9), 4GPANUMBER(3,2), 5B_DateDATE, 6MajorCHAR(4) 7);

7 Data Definition Language Name: User Identifiers: 1-30 characters Start with an alphabet Followed by alphabet, digit, _ Unique Not reserved Not case sensitive

8 Oracle Data Types: –Built-in Datatypes –ANSI Supported Datatypes –Oracle Supplied Datatypes –User-Defined Types –External Datatypes

9 Example of Oracle Data Types: –CHAR(size) –VARCHAR2(size) –NUMBER(n,d) –DATE –LONG –ROW(size) –CLOB BLOB BFILE –XML –XML index

10 Built-in Data Types: 1- Character : Format: CHAR [ (size [ BYTE/CHAR ] )] VARCHAR2 (maxsize [ BYTE/CHAR ] ) ‘4321’ ‘19 Main St. Frostburg’ ‘ * ’ ‘Student’’s ID’

11 Built-in Data Types: 2-Number: Format:NUMBER [ (Precision] [, Scale] )] NUMBER NUMBER(P,S) 3-Date (&Time): Format:DATE MyBirthdate = ‘11-JAN-37’ TIMESTAMP

12 Built-in Data Types: 4-Large Objects: Format:BLOB CLOB BFILE CREATE TABLE add_cosc_F08 (titleVARCHAR2(80), compositeBLOB, textCLOB, graphBFILE);

13 Built-in Data Types: 5-ROWID: Format:ROWID

14 ANSI Supported Data Types: Examples: CHAR CHARACTER VARCHAR NUMERIC DECIMAL INTEGER INT FLOAT REAL ……

15 Oracle Supplied Data Types: Any Type: SYS.ANYDATA SYS.ANYTYPE SYS.ANYDATASET XML Type: XMLType URLType Media Type: ORDAudio ORDImage ORDDoc

16 DESCRIBEStudent; NameNull?Type NAMEVARCHAR2(80) IDNUMBER(9) GPA…… Display a Structure of a Table:

17 Tables User Tables: 1. USER_ 2. ALL_ 3. DBA_ 4. V$_  Data Dictionary 1.USER_TABLES 2.USER_OBJECTS 3.USER_CATalog

18 Integrity Constraints Not Null Unique Primary Key Foreign Key Check -Why Integrity Constraints?

19 Integrity Constraints Inline (Col_Constraint) Out_of_line(Table_Constraint) NOT NULL

20 Integrity Constraints 1.NOT NULL: CREATE TABLE student (NameVARCHAR2(80)NOT NULL, IDNUMBER(9)NOT NULL, GPANUMBER(3,2), B_DateDATE, MajorCHAR(4));

21 Integrity Constraints Constraints on Tables:Why? NOT NULL: CREATE TABLE student (NameVARCHAR2(80)NOT NULL, IDNUMBER(9)NOT NULL, GPANUMBER(3,2), B_DateDATE, MajorCHAR(4));

22 Integrity Constraints UNIQUE: CREATE TABLE student (NameVARCHAR2(80) UNIQUE NOT NULL, IDNUMBER(9) UNIQUE, GPANUMBER(3,2), B_DateDATE, MajorCHAR(4));

23 Integrity Constraints UNIQUE: CREATE TABLE student (NameVARCHAR2(80), IDNUMBER(9), GPANUMBER(3,2), B_DateDATE, MajorCHAR(4), UNIQUE (Name,ID) );

24 PRIMARY KEY: CREATE TABLE student (NameVARCHAR2(80), IDNUMBER(9) PRIMARY KEY, GPANUMBER(3,2), B_DateDATE, MajorCHAR(4) ); Integrity Constraints

25 Integrity Constraints PRIMARY KEY: CREATE TABLE student (NameVARCHAR2(80), IDNUMBER(9), GPANUMBER(3,2), B_DateDATE, MajorCHAR(4), PRIMARY KEY(ID) );

26 Integrity Constraints FOREIGN KEY: CREATE TABLE Course (C_NumNUMBER(4,0) NOT NULL, DeptVARCHAR2(20) REFERENCES Department(name), TitleVARCHAR2(40), CreditNUMBER(1), CONSTRAINT dep_PK PRIMARY KEY (C_Num, Dept) );

27 Integrity Constraints CREATE TABLE Course (C_NumNUMBER(4,0) NOT NULL, DeptVARCHAR2(20) TitleVARCHAR2(40), CreditNUMBER(1), CONSTRAINT dep_PK PRIMARY KEY (C_Num, Dept) CONSTRAINT dep_FK FOREIGN KEY (dept) REFERENCES Department(name) );

28 Integrity Constraints CREATE TABLE Course (C_NumNUMBER(4,0) NOT NULL, DeptVARCHAR2(20) REFERENCES Department(name) ON DELETE CASCADE, --ON DELETE SET NULL TitleVARCHAR2(40), CreditNUMBER(1), PRIMARY KEY (C_Num, Dept) );

29 Range Constraint: CREATE TABLE student (NameVARCHER2(80), IDNUMBER(9) CHECK (ID BETWEEN AND ), GPANUMBER(3,2) CHECK (GPA BETWEEN 0.00 AND 4.00), B_DateDATE, MajorCHAR(4) ); --CHECK (grade IN(‘A’, ‘B’, ‘C’, ‘D’, ‘F’)) --Constraint grade_CK CHECK (grade IN (‘A’,’B’,’C’,’D’,’F’)) Integrity Constraints

30 Integrity Constraints CREATE TABLE student (NameVARCHAR2(80) CONSTRAINT student_nnNOT NULL, IDNUMBER(9) NOT NULL, GPANUMBER(3,2), B_DateDATE, MajorCHAR(4), CONSTRAINT student_UQ UNIQUE (Name,ID) );

31 CREATE TABLE student (NameVARCHAR2(80), IDNUMBER(9), GPANUMBER(3,2) CHECK (GPA BETWEEN0.00 AND 4.00), B_DateDATE, MajorCHAR(4), CONSTRAINT student_ID_CK CHECK(ID BETWEEN AND ) ); Integrity Constraints

32 Constraints SELECT Constraint_Name, Constraint_Type, Table_Name FROM user_constraints; Constraint_NameConstraint_TypeTable_Name SYS_COU2111P student student_UQU student student_ID_CKC student dep_FKR student

33 Constraints States: DISABLE ENABLE Integrity Constraints

34 Integrity Constraints CREATE TABLE student (NameVARCHAR2(80) CONSTRAINT student_nnNOT NULL DISABLE, IDNUMBER(9) NOT NULL DISABLE, GPANUMBER(3,2), B_DateDATE, MajorCHAR(4), CONSTRAINT student_UQ UNIQUE (Name,ID) DISABLE );

35 Default CREATE TABLE Course (C_NumNUMBER(4,0) Default ‘XXXX’ NOT NULL, DeptVARCHAR2(20) REFERENCES Department(name) ON DELETE CASCADE, TitleVARCHAR2(40), CreditNUMBER(1).DEFAULT 3, PRIMARY KEY (C_Num, Dept));

36 Default CREATE TABLE Temp ( inserts VARCHAR2(80) DEFAULT USER, arrived DATE DEFAULT SYSDATE, loggedInAs NUMBER(4) DEFAULT UID );

37 Create table from a table CREATE TABLE tempstudent AS SELECT Name,ID,GPA, B_Date FROM student;

38 Delete a Table: DROP TABLE Student; DROP TABLE Student CASCADE CONSTRAINTS; DROP TABLE Student PURGE; TRUNCATE TABLE Student; PURGE TABLE Student;

39 –Privilege is required –DESC student; –DROP TABLE student CASCADE CONSTRAINTS; –SELECT * FROM RECYCLEBIN; -- USER_RECYCLEBIN Flash_back

40 Object_Name Original_Name Operation Type TS_Name RB$$48448$TABLE$0 STUDENTDROP TABLE USERS Creation Droptime :14:11: :12:30:31 Flash_back

41 Restoring Tables from Recycle Bin: FLASHBACK TABLE Student TO BEFORE DROP RENAME TO Student2;

42 Changing an existing Table Structure 1.Adding Columns: ALTER TABLE student ADD (AddressVARCHAR2(50), PhoneCHAR(10) ); 2.Modify Table Condition: ALTER TABLE student MODIFY (IDNUMBER(10,0), NameVARCHAR2(200) ); (continued)

43 Changing an Existing Table Structure 3. Deleting Columns: ALTER TABLE student DROP COLUMN Address; ALTER TABLE student DROP COLUMN (Major, Minor); 4. Modify Table Condition: ALTER TABLE student SET UNUSED COLUMN Address;

44 Renaming Table Columns 5. ALTER TABLE student RENAME COLUMN ID TO NewID;

45 Rules for Adding and Modifying: You can add columns with no NOT NULL You can increase the CHAR width You can increase the number of Digits You can increase/decrease the number of decimals You can convert CHAR to VARCHAR2 You can change data type if the column contains no values

46 Changing the name of a table: RENAME student TO GradStudent;

47 Adding Comments to a Table: COMMENT ON TABLE student IS ‘staff information’; COMMENT ON COLUMN student.column IS ‘text’;

48 Viewing information about a Table: USER_TABLES USER_TAB_COLUMNS USER_ALL_TABLES USER_TAB_COMMENTS USER_COL_COMMENTS USER_TAB_STATISTICS USER_TAB_MODIFICATIONS ALL_TABLES DBA_TABLES

49 Querying Data SELECT * FROM USER_TABLES; SELECTDISTINCT object_type FROMuser_object; SELECT* FROMcat;

50 Add a constraint to an existing table: ALTER TABLE student ADD CONSTRAINT student_pk PRIMARY KEY (ID);

51 Drop a Constraint: ALTER TABLE student DROP CONSTRAINT student_pk ; (if you did not name your constraint) ALTER TABLE student DROP PRIMARY KEY; ALTER TABLE student DROP CONSTRAINT student_pk CASCADE;

52 Constraints: Disable a constraint: ALTER TABLE student DISABLE CONSTRAINT student_pk ; Enable a constraint: ALTER TABLE student ENABLE CONSTRAINT student_pk;

53 Constraints ALTER TABLE student ENABLE PRIMARY KEY ENABLE UNIQUE (Name) ENABLE UNIQUE (Phone) ENABLE Student_ID_CK;

54 Constraints: You may enable or disable your Constraint: CREATE TABLE student (NameVARCHER2(80), DISABLE CONSTRAINT student_nn NOT NULL, IDNUMBER(9) NOT NULL, GPANUMBER(3,2), B_DateDATE, MajorCHAR(4), CONSTRAINT student_uk UNIQUE (Name,ID) );

55 Constraints: NOTE: Automatic system constraint naming: System ID SYS_C###### Viewing constraints: SELECT constraint_name,constraint_type FROM user_constraints; Viewing constraints: SELECT constraint_name,constraint_type FROM user_constraints WHEREtable_name= ‘ STUDENT ’ ;

56 Constraints: Viewing column constraints: SELECT constraint_name, column_name, constraint_type FROM user_cons_columns; Viewing column constraints: SELECT constraint_name, column_name, FROM user_cons_columns WHEREtable_name= ‘ STUDENT ’ ;

57 Constraints: Example: SELECT * FROM USER_COL_COMMENTS; DROP COMMENTS: COMMENT ON COLUMN student.id IS ‘ ’ ;

58 Encrypted Columns CREATE TABLE student (NameVARCHAR2(80) PRIMARY KEY, IDNUMBER(9) ENCRYPT, GPANUMBER(3,2), Reg_Date DATE DEFAULT (SYSDATE), MajorCHAR(4)) TABLE SPACE mytables STORAGE (INITIAL 50k);

59 Temporary Tables –You can create tables that solely exist for your session or whose data persists for the duration of your transactions. –Use CREATE GLOBAL TEMPORARY TABLE; you can specify whether it should last for the duration of your session (via ON COMMIT PRESERVE ROWS) (Session specific) or should be deleted when transaction is complete (via ON COMMIT DELETE ROWS) (Transaction specific)

60 CREATE GLOBAL TEMPORARY TABLE myTable ( col 1 Type 1 col 2 Type 2 col 3 Type 3 ) ON COMMIT PRESERVE ROWS; Temporary Tables

61 Case Study One –A web-based student registration application allows a student to create several options course schedule for a given semester. Each option will be a row in a Temporary Table. When a student decides which option s/he wants to select, the application moves the row from the Temporary Table to a permanent table. –During the session, the course data are private. At the end, data are dropped.

62 CREATE GLOBAL TEMPORARY TABLE student_work_area ( Course1CHAR(11) --COSC Course2CHAR(11) Course3CHAR(11) Course4CHAR(11) Course5CHAR(11) Day1CHAR(1) --T Day2CHAR(1) Day3CHAR(1) Day4CHAR(1) Day5CHAR(1) Start_Time1NUMBER(5,2) End_Time1NUMBER(5,2) Start_Time2NUMBER(5,2) End_Time2NUMBER(5,2) Start_Time3NUMBER(5,2) End_Time3NUMBER(5,2) Start_Time4NUMBER(5,2) End_Time4NUMBER(5,2) Start_Time5NUMBER(5,2) End_Time5NUMBER(5,2)) ON COMMIT DELETE ROWS;

63 PRACTICE This code compile: DECLARE Sysdate NUMBER; BEGIN Sysdate:=2; END; This code dose not compile: DECLARE then NUMBER; BEGIN then:=2; END; WHY?