1. SQL, Data Storage Technologies, and Web-Data Integration
Week 3

2. Today’s Agenda Questions? Review Physical Database Design
Connecting to MySQL
Introduction to SQL

3. Week 2 Review 2nd Normal Form 3rd Normal Form Physical database design
Attributes must be dependent on the unique attributes
3rd Normal Form
Non unique attributes cannot be dependent on each other
Physical database design
Entities become tables
Attributes become columns
Unique IDs become primary keys
Relationships become foreign keys

4. Data Types Each database has its own data types
Most share a common core of data types, including integers, character strings, and dates.
MySQL has 36 different data types

5. Data Types Numeric Types
store numeric data such as integers and floating point numbers
Modifiers:
UNSIGNED: 0 to 255 instead of -128 to 127
AUTO_INCREMENT: integers only, one per table

6. Data Types
Numeric Types Cont.

7. Data Types String Types store textual data. Modifiers:
BINARY: allows case-sensitive searching

8. Data Types
String Types Cont.

9. Data Types
Date types
store dates and times

10. Data Types Complex data types Enumerations (ENUM) Sets (SET)
list of predefined strings, value must be one of them.
Sets (SET)
list of predefined strings, value can be any combination of them.

11. Current Physical Database Design
Donor
DonorID
Name
address
Phone number
Processor
ProcessorID
name
Division
DivisionID
name
Donation
DonationID
Date
Amount
DonorID
ProcessorID
DonationToDivision
DonationToDivisionID
Percentage
DonationID
DivisionID

12. New Physical Database Design
Donor table: includes types!

13. Physical Database Design
Choosing Column Options
Column options help enforce data integrity
Can make the programmer’s job easier
Which makes the DBA’s job easier
Column Options
NULLs allowed, default values, auto incrementing values, and keys

14. Column Options NOT NULL
By default, columns can contain a NULL instead of a value; this overrides that behavior
Requires that some value always exists in that column for any given row of data.
Will cause a database error if the programmer tries to add a NULL to that column.
What should be NOT NULL in our donation ER diagram?

16. Column Options DEFAULT value
If a user doesn’t supply a value for a column, you can specify a default value
Example: For a local organization, State and Country might default to WA, USA
Should there be any DEFAULT columns in our donation database?

17. Column Options AUTO_INCREMENT
Provides a default value to an INTEGER column
The value will automatically be incremented for each insert
Only one column per table can have this option.
Great option for an internal (meaning not shown to a external user) primary key

18. Column Options PRIMARY KEY UNIQUE Creates an index on the column
Forces each column entry to be unique from all other column entries
Automatically is NOT NULL
UNIQUE
Just like PRIMARY KEY, without the special name.

19. Physical Database Design
Now includes column options!

20. Relational Database Schema
We now have our database schema
Whereas our E/R Diagram was very abstract, we now have a very concrete, relational design

21. In Class Exercise Turn your Data Models into Database Schemas: Recipes
Dating Service
Bookstore
Photo Sharing
Movie Collection

22. The MySQL RDBMS
Connecting to MySQL
Using SQL commands

23. Client/Server Architecture
A distributed system of computing between two or more programs
Clients initiate requests, servers respond to requests
MySQL is an example of a server
The World Wide Web is an example of a vast client/server application

24. Multiple Clients
Most servers, such as MySQL, support multiple clients connecting at the same time

25. An example GUI Client

26. Connecting to MySQL Log in to the course server: Log in to MySQL
SSH homer.u.washington.edu
Username: student8
Select ‘O’ then ‘W’
Log in to MySQL
$ mysql/bin/mysql –u uwnetid –p

27. Using the mysql Client
We are now connected as a client of the MySQL server.
The mysql prompt acts just the Unix prompt (almost)
Commands must end with a semicolon
MySQL can hold more than one database
How do we know what they are all called?
mysql> show databases;

28. Using Your Database
Each one of you has your own database in the MySQL server, named with your UW NetID
Tell MySQL which database you want to use for your commands
mysql> use database_name;
where database_name is your UW NetID

29. Conventions Table names in StudlyCaps Columns names in all_lower_case
case sensitive in newer versions of MySQL
Columns names in all_lower_case
except for PRIMARY_KEY_ID and FOREIGN_KEY_ID
not case sensitive
In general, SQL user defined names must:
follow the file naming rules of the underlying OS
should only contain only letters, underscores, or digits
not be a SQL reserved word (no columns named “null”, for example)

30. Creating a Table SQL Syntax CREATE TABLE TableName (create_clause, …)
Where create_clause = column_name DATATYPE [MODIFIER ]*

31. Creating a Table mysql> CREATE TABLE Donor (
DONORID INT UNSIGNED PRIMARY KEY AUTO_INCREMENT,
name VARCHAR(255) NOT NULL,
VARCHAR(255),
phone_number VARCHAR(14),
address VARCHAR(255) );

32. Creating a Table If everything went smoothly, you should see:
Query OK, 0 rows affected (0.00 sec)
If something went wrong, you’d see something like:
ERROR 1064: You have an error in your SQL syntax. Check the manual that corresponds to your MySQL server version for the right syntax to use near 'your SQL statement here' at line 1

33. Describing and Destroying Tables
Listing all the tables
mysql> SHOW TABLES;
Describing an existing table
DESCRIBE TableName;
mysql> DESCRIBE Donor;
Destroying a table
DROP TABLE TableName;
mysql> DROP TABLE Donor;

34. Basic SQL Commands
INSERT
SELECT
Being choosy
DELETE
UPDATE

35. Inserting Data SQL Syntax Example
INSERT INTO TableName [ (column,…) ] VALUES ( values, … );
INSERT INTO TableName SET column=value, ….;
Example
mysql> INSERT INTO Donor (name, ) VALUES (‘Jake Johnson’,

36. Inserting Data
All values must be quoted except for numerical data types
“Jake Johnson”
“ ”
Quotes must be escaped
“He said, \”yes,\” and continued along.”
‘Jake\’s House of Blues’

37. Inserting Data Inserting multiple rows
mysql> INSERT INTO Donor (name, , phone_number) VALUES (‘John Smith’, ’ ’), (‘Betty Wilson’, NULL);
Use NULL when you don’t have the value
Not part of the ANSI SQL Standard
Why would this form be bad to use in an application?

38. Inserted Data A row of data in a table is called a tuple.
Schema vs. Instance
Schema is a description of a table, such as name and attributes (fairly static)
Donor(DONORID, name, , address, phone)
An instance is a tuple or set of tuples for that table (subject to frequent change)
(31, “Jake Johnson”, NULL, NULL)

39. Selecting Data Syntax SELECT column_name,… FROM TableName
Use a “*” in place of the column_name list to retrieve all columns
Examples:
Show me all the data stored about our donors
mysql> SELECT * FROM Donor;
What are all the names of all our donors?
mysql> SELECT name FROM Donor;

40. Being More Specific Syntax
SELECT column_name,… FROM TableName WHERE statement
Example
Show me all the donors with the name “Jake Johnson”
mysql> SELECT * FROM Donor WHERE name = ‘Jake Johnson’

41. Conditional Operators
SQL Symbol
Definition =
Matches if the values are equal !=
Matches if the values are not equal
>
Matches if the left value is greater than the right value
<
Matches if the left value is less than the right value
>=
Matches if the left value is greater than or equal to the right value
<=
Matches if the left value is less than or equal to the right value
IN (value,…)
Matches if value is among the values listed
BETWEEN value AND value
Matches if value is between value1 and value2 or equal to one of them.
LIKE
Matches if value matches the pattern expressed in value1 using any series of wildcard characters and anchors.

42. The LIKE comparison Uses wildcard characters to match column data
‘_’ represent any one character
SELECT name FROM Donor WHERE name LIKE ‘_ob’
Matches for “Bob”, “Rob”, “Job”, etc.
‘%’ represents any number of characters
Select name FROM Fruit WHERE name LIKE ‘%apple’
Matches for “Pineapple” and “Apple”

43. More LIKE mysql> SELECT * FROM Donor WHERE name LIKE ‘J%’;
Find all donors whose name starts with a "J”:
mysql> SELECT * FROM Donor WHERE name LIKE ‘J%’;
Use “AND” or “OR” to add multiple restrictions in your WHERE clause
Find all donors whose name starts with a “J” and have a 206 area code
mysql> SELECT * FROM Donor WHERE name LIKE “J%” AND phone_number LIKE “206%”;

44. Other Constraints
ORDER BY
LIMIT
GROUP BY
Fun with aggregates
HAVING

45. Ordering Your Data Syntax Example
SELECT column_name,… FROM TableName ORDER BY column_name, …
Example
List all donors in alphabetical order
mysql> SELECT * FROM Donor ORDER BY name;

46. More Ordering
Feel free to combine with other constraints, such as WHERE
mysql> SELECT * FROM Donor WHERE name like ‘J%’ ORDER BY name;
You can order by more than one column
SELECT * FROM Donor ORDER BY lastname, firstname
Swap the order with DESC or ASC
mysql> SELECT * FROM Donor WHERE name like ‘J%’ ORDER BY name DESC;

47. Limit Your Data Syntax Example
SELECT FROM column_name,… FROM TableName LIMIT number_of_rows
Example
Show me just two “random” donors
mysql> SELECT * FROM Donor LIMIT 2;

48. More Limiting
You can use LIMIT start, number_of_rows to specify which rows from the result set to return
Show me all the donors whose name starts with J, in alphabetical order, one at a time
mysql> SELECT * FROM Donor WHERE name LIKE ‘J%’ ORDER BY name LIMIT 0,1
mysql> SELECT * FROM Donor WHERE name LIKE ‘J%’ ORDER BY name LIMIT 1,1

49. Grouping your data
The GROUP BY clause groups data together so that aggregate functions can be performed on it.
Very common for reports and statistics
More interesting with large sets of data

50. Piping SQL commands to MySQL
Sometimes we have a big file of SQL commands that we want to run.
Download “donation.sql”, and SCP to your root dante folder
Quit your mysql client application
mysql> quit;
Use a Unix “pipe” to send the file of commands to MySQL
$ mysql/bin/mysql –u uwnetid –p uwnetid < donation.sql
The “<“ operator takes all the lines of text from donations.sql, and sends them to MySQL

51. Back to Grouping What does the Donation table look like?
mysql> DESCRIBE Donation;

52. Group By Syntax Example
SELECT column_name,… FROM TableName GROUP BY column_name, …
Example
What is the total amount donated by each donor?
mysql> SELECT donorid, SUM(amount) FROM Donation GROUP BY donorid;

53. GROUP BY with other constraints
GROUP BY must come after any WHERE clause
GROUP BY must come before any LIMIT or ORDER BY clause

54. The Groupies Aggregate Function Definition AVG(column)
Returns the average of the column values.
COUNT(column)
Returns the number of times the column was not null or had a value.
MAX(column)
Returns the maximum value of the column.
MIN(column)
Returns the minimum value of the column.
STD(column)
Returns the standard deviation of the column values.
SUM(column)
Returns the sum of the column values.

55. GROUP BY
SELECT column_name (or aggregate function), … FROM TableName WHERE clause GROUP BY column_name, …
You can GROUP BY multiple columns
Example:
How many of our donors have the same name?
SELECT fname, lname, COUNT(*) FROM Donor GROUP BY fname, lname;

56. HAVING clause
Syntax
SELECT FROM column_name,… FROM TableName HAVING statement
“statement” is the same set of conditionals that the WHERE clause has
So what is the difference between HAVING and WHERE?

57. HAVING vs. WHERE
The WHERE clause happens as MySQL is looking through its table
The HAVING clause happens on the rows returned by the WHERE clause
mysql> SELECT * FROM Donor HAVING name = ‘Jake Johnson’;
Twice as slow! First scan the Donor table for all the rows, then scan all the rows again for names matching ‘Jake Johnson’.

58. HAVING
Let's say we're interested in sending a letter to our top donors – those who donated more than $150.
Use the GROUP BY clause and the SUM aggregate function to get a list of the total amounts.
Adding the HAVING clause we can further restrict the results.
mysql> SELECT donorid, SUM(amount) FROM Donation GROUP BY donorid HAVING SUM(amount) > 150;

59. Deleting rows Syntax Example DELETE FROM TableName [whereclause]
mysql> DELETE FROM Donation;

60. Deleting is too Easy! Rows are hard to create, easy to destroy!
Always use a WHERE clause!
Example:
mysql> DELETE FROM Donor WHERE name = ‘Jake Johnson’;
Best to write a SELECT first

61. Updating data
Syntax
UPDATE TableName SET column_name = value [where_clause]
Let’s learn our lesson from delete, and always use the WHERE clause
Example:
mysql> UPDATE DONOR SET address = ‘123 Home Lane’, phone_number = ‘ ’ WHERE Donorid = 1;

62. Using the Aggregates How many donations has each donor made?
What is the maximum donation amount made by each donor?
What are the donorIDs for the top ten donors?
Of those who donated in 2003, what are the donorIDs of the ten worst donors in 2003?
What is the total amount of donations we’ve received in 2004?
What are the donorIDs for the ten best and ten worst donors?