IS 380 Introduction to SQL This lectures covers material from: database textbook chapter 3 Oracle chapter: 3,14,17

2 IS 380, A. M. Thomason Objective Understand the basics of database languages Learn how to manipulate and manage a database using SQL

3 IS 380, A. M. Thomason Structure query Language SQL meets ideal database language requirements: –SQL coverage fits into several categories: (1) Data Definition (DDL): Ex: Create Table (2) Data Management (DML).Ex: Delete (3) Data Query. (4) Transaction Control (5) Data Control Language (DCL) –SQL is relatively easy to learn. 4 th Gen. Language –ANSI prescribes a standard SQL.

4 IS 380, A. M. Thomason Why Study SQL? The ANSI standardization effort has led to a de facto query standard for relational databases. SQL has become the basis for present and expected future DBMS integration efforts. SQL has become the catalyst in the development of distributed databases and database client/server architecture.

5 IS 380, A. M. Thomason SQL Data Definition Data Management Data Query.

6 IS 380, A. M. Thomason Data Definition Create a database Create a Table columns names, data types Delete a table structure Modify a columns data type

7 IS 380, A. M. Thomason Data Management Insert New records Modify existing records delete records

8 IS 380, A. M. Thomason Query Allows you to ask the database questions or view the table from different perspectives and criterion without modifying the content.

9 IS 380, A. M. Thomason Creating Tables CREATE TABLE [user.]table (column datatype [DEFAULT expr] [column_constraint], … [table_constraint]); Rules: name can be no longer than 18 characters the name must start with a letter No spaces allowed Underscores are alright to use.

10 IS 380, A. M. Thomason Creating a Simple Table Create table t (fd_name1 fd_type, fd_name2 fd_type, …); Example: Create table customer (ssn char(9), customername char(30), customeraddress char(30), amount number(10,2));

11 IS 380, A. M. Thomason Data types Char(n) - SQL specific varchar(2) - Text field variable lengh date number(x,n) See page 1060 in Oracle book for Oracle specific

12 IS 380, A. M. Thomason Deleting a Table Drop Table t Example: drop table customer

13 IS 380, A. M. Thomason Deleting records but not definition Truncate table t Example: Truncate table customer

14 IS 380, A. M. Thomason Adding new attributes (Columns) Alter table t add (fx fd_type, fy fd_type); Example: alter table customer add (zip char(5), phone char(10));

15 IS 380, A. M. Thomason Modify column definition Alter table table_name modify (fl newtype, f2 new_type,…); Example: alter table customer modify (customername char(50));

16 IS 380, A. M. Thomason Display the table structure Describe t; Example: describe customer;

17 IS 380, A. M. Thomason Data Management- insert records Insert into t values (f1value, f2value,, …); insert into t (f1, f2,…) values (f1value, f2value,…);

18 IS 380, A. M. Thomason Data Management- delete Delete from t where [conditions];

19 IS 380, A. M. Thomason Data Management- Update update t set f1=newvalue, f2=newvalue where [conditions];

20 IS 380, A. M. Thomason Data Management- save and Undo Commit; saves your date rollback; undo, save to last last commit status

21 IS 380, A. M. Thomason Copy contents from one table to another Insert into to-tableselect * from from-table; insert into to-table (column1, column2, …) select column1, column2,… from from table;

22 IS 380, A. M. Thomason Data Queries-display records Select * from t; selects all records from table t Select * from t where [conditions]; Select * from t f1, f2, …. Where [conditions];

23 IS 380, A. M. Thomason Conditions Mathematical and logical operators = <> > < >= <=

24 IS 380, A. M. Thomason Conditions-continued Mathematical and logical operators and or not Example: ….where price > 10; where price is > 10 and code <> 1234;

25 IS 380, A. M. Thomason Nulls and Not Nulls –Nulls: Is used when the values for one or more columns are unknown. This is not the same as spaces. SQL handles the problem of not having a value by allowing this special value to represent an unknown or nonapplicable. It is known as a null data value. When defining the table structure it can be assigned. –Not nulls is used for such situations a a key field. Where you do want to make sure a value is entered.

26 IS 380, A. M. Thomason Constraints - advance Column Constraints column [CONSTRAINT constraint_name] constraint_type, Table Constraints [CONSTRAINT constraint_name] constraint_type (column, …), If constraint is a foreign key, follow this syntax: [FOREIGN KEY] (column, …) REFERENCES table [ (column, …) ] [ON DELETE CASCADE] Constraint Types: –NOT NULL –UNIQUE –PRIMARY KEY –FOREIGN KEY –CHECK

27 IS 380, A. M. Thomason Sample Tables VENDOR and PRODUCT 1:M relationship Some characteristics to note –The VENDOR table contains vendors who are not referenced in the PRODUCT table. PRODUCT is optional to VENDOR. –All V_CODE values in the PRODUCT table must have a match in the vendor table. –A few products are supplied factory-direct, a few are made in-house, and a few may have been bought in a special warehouse sale. That is, a product is not necessarily supplied by a vendor. VENDOR is optional to PRODUCT.

28 IS 380, A. M. Thomason CREATE TABLE VENDOR (VEN_CODEINTEGER, VEN_NAMEVARCHAR2(35) CONSTRAINT VENDOR_VEN_NAME_NN NOT NULL, VEN_CONTACTVARCHAR(15)CONSTRAINT VENDOR_VEN_CONTACT_NN NOT NULL, VEN_AREACODECHAR(3)CONSTRAINT VENDOR_VEN_AREACODE_NN NOT NULL, VEN_PHONECHAR(8)CONSTRAINT VENDOR_VEN_PHONE_NN NOT NULL, VEN_STATECHAR(2)CONSTRAINT VENDOR_VEN_STATE_NN NOT NULL, VEN_ORDERCHAR(1)CONSTRAINT VENDOR_VEN_ORDER_NN NOT NULL, CONSTRAINT VENDOR_VEN_CODE_PK PRIMARY KEY (VEN_CODE)); Create Table Examples - vendor Table

29 IS 380, A. M. Thomason CREATE TABLE PRODUCT (PROD_CODEVARCHAR(10), PROD_DESCRIPTVARCHAR(35)CONSTRAINT PRODUCT_PROD_DESCRIPT_NN NOT NULL, PROD_INDATEDATECONSTRAINT PRODUCT_PROD_INDATE_NN NOT NULL, PROD_ONHANDINTEGERCONSTRAINT PRODUCT_PROD_ONHAND_NN NOT NULL, PROD_MININTEGERCONSTRAINT PRODUCT_PROD_MIN_NN NOT NULL, PROD_PRICENUMBER(8,2)CONSTRAINT PRODUCT_PROD_PRICE_NN NOT NULL, PROD_DISCOUNTNUMBER(4,1)CONSTRAINT PRODUCT_PROD_DISCOUNT_NN NOT NULL, VEN_CODEINTEGER, CONSTRAINT PRODUCT_PROD_CODE_PK PRIMARY KEY (PROD_CODE), CONSTRAINT PRODUCT_VENDOR_VEN_CODE_FK FOREIGN KEY (VEN_CODE) REFERENCES VENDOR); Create Table Examples - Product Table

30 IS 380, A. M. Thomason Additional SQL commands Between like Order by Views In Null Union, Intersect, Minus (Page 292 in Oracle book)

31 IS 380, A. M. Thomason Between Select pnum from product where price between 10 and 20;

32 IS 380, A. M. Thomason Like Compares to similar character string % represents any group of characters _ represents one character Ex: … where name like ‘s%’; ….where name like ‘_llen’;

33 IS 380, A. M. Thomason Like Compares to similar character string % represents any group of characters _ represents one character Ex: … where name like ‘s%’; ….where name like ‘_llen’;

34 IS 380, A. M. Thomason Order by Default is ascending … order by f1; For descending: ….order by f1 desc;

35 IS 380, A. M. Thomason Views A definition of a restricted portion of a table. Create view accounting as select column1 column2 where price < 100 from Payroll;

36 IS 380, A. M. Thomason In Select employee payrollno phone from accounting where department in (‘IS’, ‘Purchasing’, ‘Benefits’); The statement above selects those employees who work in either IS, Purchasing or benefits. You may also use not in.

37 IS 380, A. M. Thomason Null Select employee payroll phone from accounting where department is not null; Select employee payroll phone from accounting where department is null; The following would be incorrect Select employee payroll phone from accounting where department =null;.