is 380 introduction to sql this lectures covers material from: database textbook chapter 3 oracle...

IS 380

Introduction to SQL

This lectures covers material from: database textbook chapter 3Oracle chapter: 3,14,17

2IS 380, A. M. Thomason

Objective

• Understand the basics of database languages

• Learn how to manipulate and manage a database using SQL


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.


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.


SQL• Data Definition

• Data Management

• Data Query.


Data Definition

• Create a database

• Create a Table

• columns names, data types• Delete a table structure• Modify a columns data type


Data Management

• Insert New records

• Modify existing records

• delete records


Query

Allows you to ask the database questions or view the table from different perspectives and criterion without modifying the content.


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.


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));


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


Deleting a Table

Drop Table t

Example:

drop table customer


Deleting records but not definition

Truncate table t

Example:

Truncate table customer


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));


Modify column definition

Alter table table_name modify (fl newtype, f2 new_type,…);

Example:

alter table customer modify (customername char(50));


Display the table structure

Describe t;

Example:

describe customer;


Data Management- insert records

Insert into t values (f1value, f2value,, …);

insert into t (f1, f2,…) values (f1value, f2value,…);


Data Management- delete

Delete from t where [conditions];


Data Management- Update

update t set f1=newvalue, f2=newvalue where [conditions];


Data Management- save and Undo

Commit; saves your date

rollback; undo, save to last last commit status


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;


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];


Conditions

Mathematical and logical operators

• =

• <>

• >

• <

• >=

• <=


Conditions-continued

Mathematical and logical operators

• and

• or

• not

Example:

….where price > 10;

where price is > 10 and code <> 1234;


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.


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


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.


CREATE TABLE VENDOR

(VEN_CODE INTEGER,

VEN_NAME VARCHAR2(35) CONSTRAINT VENDOR_VEN_NAME_NN NOT NULL,

VEN_CONTACT VARCHAR(15) CONSTRAINT VENDOR_VEN_CONTACT_NN NOT NULL,

VEN_AREACODE CHAR(3) CONSTRAINT VENDOR_VEN_AREACODE_NN NOT NULL,

VEN_PHONE CHAR(8) CONSTRAINT VENDOR_VEN_PHONE_NN NOT NULL,

VEN_STATE CHAR(2) CONSTRAINT VENDOR_VEN_STATE_NN NOT NULL,

VEN_ORDER CHAR(1) CONSTRAINT VENDOR_VEN_ORDER_NN NOT NULL,

CONSTRAINT VENDOR_VEN_CODE_PK PRIMARY KEY (VEN_CODE));

Create Table Examples - vendor Table


CREATE TABLE PRODUCT (PROD_CODE VARCHAR(10), PROD_DESCRIPT VARCHAR(35) CONSTRAINT PRODUCT_PROD_DESCRIPT_NN NOT NULL, PROD_INDATE DATE CONSTRAINT PRODUCT_PROD_INDATE_NN NOT NULL, PROD_ONHAND INTEGER CONSTRAINT PRODUCT_PROD_ONHAND_NN NOT NULL, PROD_MIN INTEGER CONSTRAINT PRODUCT_PROD_MIN_NN NOT NULL, PROD_PRICE NUMBER(8,2) CONSTRAINT PRODUCT_PROD_PRICE_NN NOT NULL, PROD_DISCOUNT NUMBER(4,1) CONSTRAINT PRODUCT_PROD_DISCOUNT_NN NOT NULL, VEN_CODE INTEGER, 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


Additional SQL commands

• Between• like• Order by• Views• In• Null• Union, Intersect, Minus (Page 292 in Oracle

book)


Between

Select pnum from product where price

between 10 and 20;


Like

Compares to similar character string

% represents any group of characters

_ represents one character

Ex: … where name like ‘s%’;

….where name like ‘_llen’;


Order by

Default is ascending

… order by f1;

For descending:

….order by f1 desc;


Views

A definition of a restricted portion of a table.

Create view accounting as

select column1 column2

where price < 100 from Payroll;


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.


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;.

is 380 introduction to sql this lectures covers material from: database textbook chapter 3 oracle...

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