Let’s try Oracle

Accessing Oracle

• The Oracle system, like the SQL Server system, is client / server.

• For SQL Server, – the client is the Query Analyser application installed in

all machines in the COMP domain labs.– The server is on CIAN.STUDENT.COMP.DIT.IE

• For Oracle,– The client is either:

• The SQL*PLUS application installed on all machines in the COMP domain labs.

• iSQLPlus, which can be accessed using a Web Browser while attached to the COMP domain.

– The Server is on FERDIA.STUDENT.COMP.DIT.IE

Starting with Oracle

SQL Plus

Today in the lab…

• Connect to SQL Plus – your schema.

• Set up a table.

• Find the table in the catalog.

• Insert four rows into the table.

• Run various different select statements on the table.

Find your feet…

• Oracle SQL Plus– Are you in the correct lab?– Introduce yourselves to Oracle

• Each person has an individual schema (R,W,U,D)• In your INDIVIDUAL schema, use the Data

Definition Language commands to create, and populate, update the table.

Find the application

• Through the Start menu, find– Programs– Oracle client– Application

Development– SQL Plus (icon

opposite)

Sqlplusw.exe

This is an example

• Don’t forget to get a username and password for your SCHEMA.

• The Host string defines the DATABASE. – The host string is oracledb

An example from Oracle 10g

About the interface…

• The interface is VERY basic. It is similar to a very old model of command line interface.

• Each line is transacted immediately.

• It takes a bit of getting used to!

• Create the same book table that you did on SQL Server.

…About the interface

• To exit the application, type in EXIT

• To save your work:• It is messy trying to save

in this environment.• The best thing to do is to

open Notepad as well as SQL Plus and copy from one to the other.

• Note that the full path name needs to be entered, so keep path names SHORT!!.

SQL differences you will see

• SQL or Structured Query Language is used widely to access databases.

• Implemented SQL (Oracle, MS SQL Server, Access) varies a little from the standard, but is reasonably standard

• Every query ends with a semi-colon ‘;’• The functions in Oracle differ from those in SQL Server.• The datatype VARCHAR in SQL Server is replaced by the

datatype VARCHAR2 in Oracle.• Numeric data types are represented by NUMBER(L,P)

where L is the full length, in digits, of the number and P is the number of those digits that are after the decimal point. E.g. NUMBER(6,2) can take up to 9999.99.

The CREATE command

• Creates tables in your schema.• The basic Create statement:CREATE TABLE table_name({column_name data_type})• [] optional, {} one or more, lower case – user supplied

names, upper case reserved words, [|] either or, () are part of the syntax.

• See www.ss64.com/orasyntax/datatypes.html for a comprehensive list and description of data types.

Data Manipulation Language

• Data Manipulation language (DML) allows you to manipulate the contents of the tables in you schema, rather than the definition.

• DML includes– Insert– Delete– Update– Select

Insert statement

• This adds data to the table.• Either a full row can be added, or values can be

put in individual columns.• NOTE: If only some of the columns are given

values, the remainder of the columns have an undefined status of NULL.

• If a column is constrained by the ‘NOT NULL’ constraint, every insert to the owning table must provide a value for that column, unless a DEFAULT value is provided for the table.

Manipulating the buffer• To terminate an entry, use ; or, on a new line, use /• Append text or a text adds text to the end of a line.• Change /old/new or C /old/new changes old to new in a line.• Change /text or C /text deletes text from a line.• Clear buffer or cl buff deletes all lines.• Del deletes a line• Get file loads the contents of a fine named file into the buffer.• Input or i add one or more lines• Input text adds a line consisting of text.• List or l lists all lines in buffer• List n or l n or n lists one line and makes it the current line.• List * or l * lists the current line• List last or l last lists the last line• List m n or l m n lists lines m through n• Save file or sav file saves the contents of the buffer to a file named file.

To list columns

• select table_name, column_name from user_tab_columns;

• To describe a table:– Desc <tablename>;

Format of the CREATE

CREATE TABLE tablename

(

{column_name datatype columnconstraint,}

{tableconstraint}

)

Example

CREATE TABLE book ( ISBN VARCHAR2(13),Title VARCHAR2(40),Price NUMBER(7,2),NumberInStock NUMBER(3),Genre VARCHAR2(10),DatePublished DATE);

Dropping a table

• When you have created a table, you have set up a definition in the database of that table.

• You cannot create the table again, while the first definition is still there.

• To remove the table, use the DROP command.– DROP table BOOK;

A better CREATE

• To improve on our previous CREATE statement:– Define one of the fields as a key– Allow null values to be entered against the

number of books in stock.– Don’t allow null values to be entered against

the Title or ISBN.– Check that the Price is less that €100.– Put in a default value of ‘Drama’ for Genre.

New CREATE

CREATE TABLE book (ISBN VARCHAR2(13) NOT NULL,Title VARCHAR2(40) NOT NULL,Price NUMBER(7,2) CHECK (price < 100.00),NumberInStock NUMBER(3) NULL,Genre VARCHAR2(10) DEFAULT ‘Drama’,DatePublished DATE,PRIMARY KEY (ISBN));

Inserting data into a table

• This is done using the INSERT statement.

• The INSERT has two formats:– Full insert:

INSERT into BOOK values(‘1-56592-744-3’,’SQL in a Nutshell’,0,23.99,’Technical’,’01/01/01’)

– Or partial insert:

INSERT into BOOK(ISBN, Title,DatePublished) values(‘0-07-135953-2’,’Fundamentals of SQL Programming’,’01/01/00’)

Exercise

• Create the book table, as you did in SQL Server.– Note that some of the syntax differs.

• Insert four rows into the book table, ensuring that the data types and constraints are respected.

• Check the contents of the table– Select * from tablename;– Note that the semicolon ends the statement.

To look at the table contents..• Use the SELECT instruction:

select * from book– Literally means show everything from the book table

Exercises• Add the BOOK table to your database.• Try to insert the following rows:INSERT INTO BOOK values ('0-13-085033-0','Programming Oracle Triggers and Stored Procedures',49.99, 40, 'Computing', '01/01/2004');INSERT INTO BOOK values ('0-201-11803-0','Visual Quickstart Guide SQL',29.50, 10, 'Computing', '01/01/2002');• Find out what the errors are, and why they happened.

To add some more records:

• Oracle\ADDBOOKS.SQL