1. Intro to SQL
CS-422
Dick Steflik

2. Structured Query Language
Developed by C. Date for Relational Data Base Management Systems (RDBMS)
Simple Declarative Language
has no program control statements

3. SQL Two categories of commands Data Manipulation Commands
deal with:
RETRIEVING DATA
MAINTAINING DATA
ADDING, UPDATING, DELETING
Data Definition Commands
DEAL WITH:
CREATING DATABASE OBJECTS (TABLES,VIEWS)
Object organization and attributes

4. Data Model
Database objects are modeled on the concept of a table (i.e. rows and columns)
Each row is a single table object
Columns are the attributes of that table
A database is a collection of related tables

5. Referential Integrity
Rules to insure that table data stays accurate and accessible
rows in a table should be unique
one column should contain no duplicate data
primary key
column values cannot contain repeating groups or arrays
null is different than space and zero, 2 null values are not considered equal

6. Data Manipulation Commands
Select - query and display data from a database
Insert - a new row into a table
Update - modify a column in a table
Delete a row from a table

7. Select
Select (column list) from (sources) where (conditions) order by (ocolumn list)
column list - comma separated list of names of columns to be in output
Ex. ssn , lastname , firstname,gpa
can contain literals to be included in output
Ex. Ssn,”~”,lastname,”~”,firstname
sources - name(s) of table(s) to retrieve data from
conditions (optional) - conditions for selections
lastname like “S%”
(lastname = “Steflik) and (firstname like “R%”)
ocolumn list (optional)- list of columns that output should be ordered by Ex
select * from student
select lastname,fristname from student where gpa > 3.0
select lastname,firstname from student order by lastname,firstname

8. Select - joined tables
Two tables may be joined and viewed as a single data source is the both have a common column
suppose we have 2 tables: Inventory and category and each has a column called catg_code
In category catg_code is unique and is the primary key

9. Select - joined tables (cont.)
Inventory
Category
P_no
Catg_code
qty
Catg_code
descr

10. Select - joined tables (cont.)
To retrieve all of the part numbers and the name of the category to which the part belongs:
select inventory.p_no category.descr from inventroy , category
select a.p_no,” “,b.descr from a inventory , b category

11. Insert Add a row to a table use jdbc execute Update method
insert into category values(“IGN”,”Ignition System”)
use jdbc execute Update method
ex. Stmt.executeUpdate(“insert into Category values(‘IGN’,’Ignition System’)”);

12. Update Modify an existing row in a table Use jdbc executeUpdate method
update category set descr = “Ignition Subsystem” where catg_code = “IGN”
Use jdbc executeUpdate method
String s = “update category set descr = ‘Ignition Subsystem’ where catg_code = ‘IGN’ ”;
stmt.executeUpdate(s);

13. Delete Remove a row from a table
delete from category where catg_code = “IGN”
remove the IGN category
delete from category where catg_code like “I%”
remove all rows where catg_code starts with an “I”

14. Data Definition Commands
Create table
add a table to a database
Drop Table
remove a table from a database
Alter Table
add or delete column(s)

15. A good reference Phil Greenspun – SQL for Web Nerds