1. CSC3530 Software Technology Tutorial 4 SQL

2. SQL / RDBMS Structured Query Language 4 th Generation programming language Tell computer what to do instead of how to do An precise way to manipulate data SQL statement update insert select RDBMS – Relation DataBase Management System Oracle mySQL A system that store data in an efficient way that allow us to retrieve and update by issuing SQL statement

3. Oracle Account Login to your unix account The oracle account password is same as your unix account Login to oracle server Type> source /usr/local/oracle8i/setup Append “source /usr/local/orale8i/setup” in.cshrc file Type> sqlplus Input account and password cprjxxxx@db00 Password given in e-mail You can start executing SQL statement Supp. notes from course CSC3170 Fall 1999 http://www.cse.cuhk.edu.hk/~csc3530/sqlsup.pdf

4. Database Schema staff(code, name, phone, email, password, rank) Underline means key Generic form Table_name (field_name1, field_name2, …) codeNamephoneemailPasswordrank A1234Albertini12345678A@milan.itAbcdManager L2345Le Tissier23456789L@south.uk1234Player V3456Vernon34567890V@mu.ukwxyzPlayer

5. Create Table create table staff ( code char(10) not null, name varchar2(50), phone char(8), email varchar2(50), password varchar2(10), rank varchar2(20), primary key (code) ); Table name – staff char(10) – fixed length string (length = 10) varchar2(50) – variable length string (max. length = 50) not null – cannot be missing primary key – indicate code is unique to differentiate different records

6. Cont’d Other data type int or integer numeric(p,d) – totally p digits, with d digits on the right of decimal point float(n) – floating point number with at least n digits date – date in (4 digit) year, month, day time – time in hours, minutes and seconds Altering table that already created alter table staff drop phone alter table staff add phone varchar2(20)

7. Inserting/Deleting Records insert into staff (code, name, phone, email, password, rank) values (‘test’, ‘test’, ‘12345678’, ‘t@test’, ‘1234’, ‘Manager’); string are embraced by single quote Integer does not need to be embraced Syntax: insert into “table_name”(“fields”) values (“fields”); delete staff where name=‘Vernon’; The row with name equals Vernon is drop Syntax : delete “table_name” where “condition”;

8. Updating Records Suppose you issued an invoice, you have to subtract the items you sold from the stock update product set on_hand=on_hand-5 where code=‘B2345’; Suppose a staff change his password Update staff set password=‘newpassword’ where code=‘staffid’; Suppose an invoice need to be voided Update invoice set voided=‘true’ where invoice_number=‘abcde123’;

9. Selecting Records Product(code, category, name, on-hand, low-limit) select code,name from product where on_hand < low_limit; Syntax: select “field_name” from “table_name” where “condition”; codecategorynameOn-handLow-limit A1234PrinterCannon12341020 B2345DVJVC23453020 C3456LCDSharp34564520 D4567MouseLogitech4567220 E5678Hard diskIBM56787620 codeName A1234Cannon1234 D4567Logitech4567

10. Joint Table Query Sometimes you need to do complex query Find those suppliers that supply us the product which are out of stock now select S.name from supplier S, product P, supplying SU where S.code=SU.supplier_code and SU.product_code=P.code and P.on_hand < P.low_limit; If you don’t use join table, you may Find product-code that is out of stock Find the supplier-code that supply that product-code Find the name of supplier with that supplier-code

11. Nested Query / Partial Match Instead of join table, you can make nested query select S.name from supplier S where S.code in (select SU.supplier_code from supplying SU where SU.product_code in (select P.code from product P where P.on_hand<P.low_limit)); You want to find all product which name consist of “er” % here means any character select * from product where name like ‘%er%’;

12. Beyond The Basics Adding constraint for a table, if violated, error will occur create table product ( code char(10) not null, category varchar2(50), name varchar2(50), on_hand integer, low_limit integer, primary key (code), check (on_hand >= 0)); When you issue invoice to sell an item, you need to deduct it from the product table, error will occur if you make the on_hand < 0, so …

13. Cont’d Find the best selling product’s product_code select I.product_code from invoice_item I group by I.product_code having sum (I.qty*I.price) >=all (select sum(I1.qty*I1.price) from invoice_item I1 group by I1.product_code); To interpret First, find the sales figure of each product Second, find the product which sales figure is highest Rank the product by their sales figure select I.product_code, sum(I.qty*I.price) as sales from invoice_item I group by (I.product_code) order by sales desc;

14. OLAP OLTP – On line Transaction Processing Support daily transaction of a company Sales in the outlet Recording working hours of staff Mainly consist of update to a single table OLAP – On line Analytical Processing Decision support for an enterprise The trend of a product base on its sales figure How is the utilization of staff in a company Mainly consist of join table query (we call it view) The two query introduced previously is a simple kind of OLAP