Fox MISSpring 2011

Database

Week 6Mid-term Review

Format of Mid-term Exam

• TIME: 11:00 am -12:00• LOCATION: SP114• FORMAT:

– Multiple Choices (10-15 questions)– Q&A (4-6 questions)– ERD (1 question)

• Content ratio (approximately): BI 10-15%, ERD 30-35%, SQL 50-60%

Business Intelligence

• What is Business Intelligence (BI)?

• What’s the main role of BI in business

• List some technologies supporting BI.

• List BI skill and knowledge clusters.

• What is BI maturity?

• What are the four stages of the BI maturity model?

• Explain why BI is an architecture and a collection of integrated operational as well as decision-support applications and databases that provide the business community easy access to business data.

Mental Map of BI

Database Design

• Database Models, advantages & disadvantages• The uniqueness of relational model• The role of DBMS, DBMS functions

ERD

• Entities• Attribute• Primary key, foreign key• Relationships (1:M, M:1, M:N)• Referential integrity

Drawing ERD

• Steps:– Identify entities– Insert primary keys– Insert attributes (independence)– Identify relationships– Add bridge entity to simplify M:N relationships– Add foreign keys and build relationships

Tips: for transactional database, it’s common to connect all “physical” entities to the core transactional entity/table.

Frequent Made Mistakes

• Add wrong attributes• Add record as attributes (e.g. laptop or product

name)• Forgot to identity relationships• Couldn’t identify M:N relationships• Wrong relationships (e.g. customer<->store)• Forgot referential integrity• Loops

First Invoice

Second Invoice

32123212

234567234567

6/10/20086/10/2008

Jason Mraz72 Spring StreetNew York, NY 10012

Jason Mraz72 Spring StreetNew York, NY 10012

3930722 The Big Short Economics 20.00 1 20.00141414 Databases R Amazing IS 100.00 2 200.00 TOTAL 220.00 Tax 13.20 Grand Total 233.20

3930722 The Big Short Economics 20.00 1 20.00141414 Databases R Amazing IS 100.00 2 200.00 TOTAL 220.00 Tax 13.20 Grand Total 233.20

Third Invoice

32133213

6/4/20086/4/2008

6/12/20086/12/2008

Sunny California610 W. Ash StSan Diego , CA 92101

Sunny California610 W. Ash StSan Diego , CA 92101

455550 To the End of the Land Novel 20.00 5 100.00141414 Databases R Amazing IS 100.00 1 100.00 TOTAL 200.00 Tax 12.00 Grand Total 212.00

455550 To the End of the Land Novel 20.00 5 100.00141414 Databases R Amazing IS 100.00 1 100.00 TOTAL 200.00 Tax 12.00 Grand Total 212.00

SQL

• Database Manipulation Language (DML)SHOW TABLES, DESCRIBESELECT, *, WHERE, ORDER BYAND & ORCOUNT, DISTINCTDELETE, INSERT, UPDATEJOIN, ALIAS

• Database Definition Language (DDL)CREATE TABLE/DATABASEDROP TABLE/DATABASEALTER, PRIMARY KEY, FOREIGN KEY

SELECT, COUNT, DISTINCT, WHERE• Table: customer_list, Databse: Sakila

– Where does Judy Gray live?• SELECT *• FROM CUSTOMER_LIST• WHERE NAME= 'JUDY GRAY‘ (or NAME LIKE ‘JUDY GRAY’)

– How many countries do our customers live in?• SELECT COUNT(DISTINCT COUNTRY)• FROM CUSTOMER_LIST

– How many customers live in Egypt?• SELECT COUNT(ID)• FROM CUSTOMER_LIST• WHERE COUNTRY = 'EGYPT'

– What cities in Egypt do our customers live in?• SELECT DISTINCT CITY• FROM CUSTOMER_LIST• WHERE COUNTRY = 'EGYPT'

– How many customers live outside of the United States?• SELECT COUNT(ID)• FROM CUSTOMER_LIST• WHERE COUNTRY <> 'UNITED STATES'

LIKE, AND, ORDER BY• Table: film

– How many films are less than or equal to 90 minutes in their lengths?• SELECT COUNT(FILM_ID)• FROM FILM• WHERE LENGTH <= 90

– How many films are about astronauts?• SELECT COUNT(FILM_ID)• FROM FILM• WHERE DESCRIPTION LIKE '%ASTRONAUT%'

– List of the movie titles which are about astronauts and their length are less than 90 minutes

• SELECT TITLE• FROM FILM• WHERE (DESCRIPTION LIKE '%ASTRONAUT%') AND (LENGTH < 90)

– List of the movie titles and their length in descending order according to the length

• SELECT TITLE, LENGTH• FROM FILM• ORDER BY LENGTH DESC

INSERT, UPDATE, DELETE• Table: retail_sales_feb• Put yourself as the customer

– You bought it from Sales_rep whose name is Smith at Feb.11.2011– Your order_no is 34567 and cust_no is 3456

DESCRIBE RETAIL_SALES_TAB (you might need this statement to see data type for each field)

INSERT INTO RETAIL_SALES_FEBVALUES ('2011-2-11', 34567, 3456, ‘Yang Yang', ‘Smith', 'CB03', 'Bike', 'Sport', 1, '$250', '$250')

• Put person next to you as the customer– You don’t know anything about that person except the name and intend to fill the rest of the

fields later on– Note: you need to figure out what the key is and make it up

DESCRIBE RETAIL_SALES_TAB (Primary key should be “NO” in Null field)

INSERT INTO RETAIL_SALES_FEB (ORDER_NO, CUSTOMER)VALUES (45678, 'Joe Smith')

• You found out that the person you bought from was not Min but Smith. Correct the informationUPDATE RETAIL_SALES_FEBSET SALES_REP = 'Smith'WHERE ORDER_NO = 34567

• You want to cancel your order and make it as if it never happenedDELETE FROM RETAIL_SAELS_FEBWHERE ORDER_NO = 34567

Join• Output customer names, payment amount, CSR name,

and rental date from database sakila:

• SELECT rental.rental_date, customer.first_name, customer.last_name, payment.amount, staff_list.nameFROM rental, customer, payment, staff_listWHERE rental.rental_id=payment.rental_id AND rental.customer_id=customer.customer_id AND rental.staff_id=staff_list.ID

• You can also use table1 INNER JOIN table2 ON conditions

• In above query, how many tables are joined? Why and when are these tables joined? How are these table joined?

Alias

• Just give another name for the output values– SELECT amount FROM payment AS p– SELECT amount, amount+1 FROM payment – SELECT amount AS "original_amount", amount+1 AS

"new_amount" FROM payment

CREATE DB and TABLE• Create a database:

CREATE DATABASE database_nameExample: CREATE DATABASE my_db

• Create a table in a database:CREATE TABLE table_name(column_name1 data_type,column_name2 data_type,column_name3 data_type,....)Example: CREATE TABLE Persons(P_Id int,LastName varchar(255),FirstName varchar(255),Address varchar(255),City varchar(255))

SQL Constraints

• Constraints are used to limit the type of data that can go into a table.

• Constraints can be specified when a table is created (with the CREATE TABLE statement) or after the table is created (with the ALTER TABLE statement).

– NOT NULL

– UNIQUE

– PRIMARY KEY

– FOREIGN KEY

– CHECK

– DEFAULT

CHECK

• The CHECK constraint specifies that the column "P_Id" must only include integers greater than 0.

• CREATE TABLE Persons(P_Id int NOT NULL,LastName varchar(255) NOT NULL,FirstName varchar(255),Address varchar(255),City varchar(255),CHECK (P_Id>0))

DEFAULT

• The DEFAULT constraint is used to insert a default value into a column.

• CREATE TABLE Persons(P_Id int NOT NULL,LastName varchar(255) NOT NULL,FirstName varchar(255),Address varchar(255),City varchar(255) DEFAULT 'Sandnes')

PRIMARY KEY• The PRIMARY KEY constraint uniquely identifies each record in a database table.

– Primary keys must contain unique values.– A primary key column cannot contain NULL values.– Each table can have only ONE primary key.

• CREATE TABLE Persons(P_Id int NOT NULL,LastName varchar(255) NOT NULL,FirstName varchar(255),Address varchar(255),City varchar(255),PRIMARY KEY (P_Id))

• ALTER TABLE PersonsADD PRIMARY KEY (P_Id)

– Creates primary key constraint for P_id column– Note: If you use the ALTER TABLE statement to add a primary key, the primary key

column(s) must already have been declared to not contain NULL values (when the table was first created).

• ALTER TABLE PersonsDROP PRIMARY KEY

– Drops a PRIMARY KEY constraint

FOREIGN KEY• A FOREIGN KEY in one table points to a PRIMARY KEY in

another table.

• CREATE TABLE Orders(O_Id int NOT NULL,OrderNo int NOT NULL,P_Id int,PRIMARY KEY (O_Id),FOREIGN KEY (P_Id) REFERENCES Persons(P_Id))

• ALTER TABLE OrdersADD FOREIGN KEY (P_Id) REFERENCES Persons(P_Id)– Create a FOREIGN KEY constraint on the "P_Id" column when the

"Orders" table is already created

• ALTER TABLE OrdersDROP FOREIGN KEY P_Id– Drops a FOREIGN KEY constraint

ALTER TABLE• The ALTER TABLE statement is used to add, delete, or modify columns in an existing

table.

• ALTER TABLE table_nameADD column_name datatype constraint(optional)

• ALTER TABLE table_nameCHANGE OLD_COLUMN_NAME NEW_COLUMN_NAME datatype constraint(optional)

– Old column name and new column name can be the same.

• ALTER TABLE table_nameDROP COLUMN column_name

• ALTER TABLE PersonsADD DateOfBirth date

• ALTER TABLE PersonsDROP COLUMN DateOfBirth

• ALTER TABLE PersonsCHANGE DateOfBirth DateOfBirth year

MySQL Data Types (Text Types)Data type DescriptionCHAR(size) Holds a fixed length string (can contain letters, numbers, and special characters).

The fixed size is specified in parenthesis. Can store up to 255 characters

VARCHAR(size) Holds a variable length string (can contain letters, numbers, and special characters). The maximum size is specified in parenthesis. Can store up to 255 characters. Note: If you put a greater value than 255 it will be converted to a TEXT type

TINYTEXT Holds a string with a maximum length of 255 characters

TEXT Holds a string with a maximum length of 65,535 characters

BLOB For BLOBs (Binary Large OBjects). Holds up to 65,535 bytes of data

MEDIUMTEXT Holds a string with a maximum length of 16,777,215 characters

MEDIUMBLOB For BLOBs (Binary Large OBjects). Holds up to 16,777,215 bytes of data

LONGTEXT Holds a string with a maximum length of 4,294,967,295 characters

LONGBLOB For BLOBs (Binary Large OBjects). Holds up to 4,294,967,295 bytes of data

ENUM(x,y,z,etc.)

Let you enter a list of possible values. You can list up to 65535 values in an ENUM list. If a value is inserted that is not in the list, a blank value will be inserted.

　Note: The values are sorted in the order you enter them.

SET Similar to ENUM except that SET may contain up to 64 list items and can store more than one choice

MySQL Data Types (Number Types)

Data type Description

TINYINT(size) -128 to 127 normal. 0 to 255 UNSIGNED*. The maximum number of digits may be specified in parenthesis

SMALLINT(size) -32768 to 32767 normal. 0 to 65535 UNSIGNED*. The maximum number of digits may be specified in parenthesis

MEDIUMINT(size) -8388608 to 8388607 normal. 0 to 16777215 UNSIGNED*. The maximum number of digits may be specified in parenthesis

INT(size) -2147483648 to 2147483647 normal. 0 to 4294967295 UNSIGNED*. The maximum number of digits may be specified in parenthesis

BIGINT(size) -9223372036854775808 to 9223372036854775807 normal. 0 to 18446744073709551615 UNSIGNED*. The maximum number of digits may be specified in parenthesis

FLOAT(size,d) A small number with a floating decimal point. The maximum number of digits may be specified in the size parameter. The maximum number of digits to the right of the decimal point is specified in the d parameter

DOUBLE(size,d) A large number with a floating decimal point. The maximum number of digits may be specified in the size parameter. The maximum number of digits to the right of the decimal point is specified in the d parameter

DECIMAL(size,d) A DOUBLE stored as a string , allowing for a fixed decimal point. The maximum number of digits may be specified in the size parameter. The maximum number of digits to the right of the decimal point is specified in the d parameter

MySQL Data Types (Data Types)Data type DescriptionDATE() A date. Format: YYYY-MM-DD

　

Note: The supported range is from '1000-01-01' to '9999-12-31'

DATETIME() *A date and time combination. Format: YYYY-MM-DD HH:MM:SS

　

Note: The supported range is from '1000-01-01 00:00:00' to '9999-12-31 23:59:59'

TIMESTAMP() *A timestamp. TIMESTAMP values are stored as the number of seconds since the Unix epoch ('1970-01-01 00:00:00' UTC). Format: YYYY-MM-DD HH:MM:SS

　Note: The supported range is from '1970-01-01 00:00:01' UTC to '2038-01-09 03:14:07' UTC

TIME() A time. Format: HH:MM:SS　

Note: The supported range is from '-838:59:59' to '838:59:59'

YEAR() A year in two-digit or four-digit format.

　

Note: Values allowed in four-digit format: 1901 to 2155. Values allowed in two-digit format: 70 to 69, representing years from 1970 to 2069