1. JDBC II
IS 313 1

2. Types Java types ≠ SQL types SQL types historical
need for backwards compatibility

3. Numeric SQL types Integers Real numbers tiny int small int integer
big int
Real numbers
real
float
decimal
numeric

4. More SQL types Boolean String Binary Time bit char varchar
long var char
Binary
binary
var binary
long var binary
Time
Date
Timestamp

5. New SQL (99) Types Binary Large Object Character Large Object Array
BLOB
Character Large Object
CLOB
Array
can manipulate without copying

6. Types in JDBC Accessors to ResultSet With column name
String name = rs.getString (“Name”);
With column number
int id = rs.getInt(1);

7. Data accessors

8. INSERT statement INSERT INTO {table} VALUES ( {value1, …, valuen} );
INSERT INTO Reservations
VALUES ( 1212, #1/23/2003#, ‘Sosa’, ‘Sammy’, 2, 14, 2 ); 15

9. UPDATE statement UPDATE {table} SET {column} = {value}
WHERE { criteria }
UPDATE Reservations
SET RoomType = 4
WHERE ID = 1234; 15

10. DELETE statement DELETE FROM {table} WHERE { criteria }
DELETE FROM Reservations
WHERE ID = 9998; 15

11. JDBC Update queries No ResultSet returned Example 1 Example 2
String sql = “INSERT INTO Reservations “ +
“VALUES (100, #12/11/2003#, ‘L.L.’, ‘Bean’, 2, 2, 2);”;
int rows = stmt.executeUpdate(sql); // always 1
Example 2
String sql = “DELETE FROM Reservations WHERE (Date = #1/21/2003#);”;
int rows = stmt.executeUpdate(sql); // how many rows deleted?

12. Assembling queries Use String operators (+) to assemble queries
String sql = “INSERT INTO Reservations “ +
“VALUES (100, #12/11/2003#, “ + firstName + “, “ +
lastName + “, 2, 2, 2);”;
int rows = stmt.executeUpdate(sql);

13. Program Development
how do I start?

14. Steps Identify classes Identify properties Identify responsibilities
Identify connection / communication
Then
Top-down elaboration
Bottom-up implementation

15. Identify classes What sorts of “things” present themselves
problem description
real-world activities

16. Example Write a program reads a student id # from the command line
retrieves student information from a database
prints out the student’s enrollment information

17. Database Students table Enrollments table Id First Name Last Name
Enrollment Id
Student Id
Date
Course Number

18. Identify properties What constitutes the “state” of something?
what distinguishes it from other instances?
what does it need to “know” in order to function?

19. Identify responsibilities
What does the object do?
Always
expose properties
Other operations?

20. Identify connection / communication
What other objects need to be connected to this one?
Examples
object A collects other objects
object A calls methods of object B
object A creates object B
object A contains object B

21. Class design Arrive at Each with a set of classes coherent properties
distinct reponsibilities
well-defined relationships

22. Implementation Strategies Top-down Bottom-up
work from the problem to the steps of its solution
Bottom-up
implement the methods of each class

23. Top-down Write down how the problem can be solved Turn this into Java
using the classes you have outlined
Turn this into Java
then make each line function

24. Bottom-up For each class write instance variable for properties
implement methods