2. INTRODUCTION
 SQL (Structured Query Language) is a computer
language aimed to store, manipulate, and retrieve data
stored in relational databases.
 IBM implemented the language, originally called
Sequel, as part of the System R project in the early
1970s..
 The first commercial relational database was released
by Relational Software later becoming oracle.

3. INTRODUCTION
The SQL language has several parts:
 Data-definition language (DDL). provides
commands for defining relation schemas, deleting
relations, and modifying relation schemas.
 Interactive data-manipulation language (DML). It
includes also commands to insert tuples into, delete
tuples from, and modify tuples in the database.
 View definition. includes commands for defining
views.
 Transaction control. includes commands for
specifying the beginning and ending of transactions.

4. INTRODUCTION
 Embedded SQL and dynamic SQL. define how SQL
statements can be embedded within general-purpose
programming languages, such as C, C++, Java, PL/I,
Cobol, Pascal, and Fortran.
 Integrity. The SQL DDL includes commands for
specifying integrity constraints that the data stored in
the database must satisfy. Updates that violate integrity
constraints are disallowed.
 Authorization (DCL). The SQL DDL includes
commands for specifying access rights to relations and
views.

6. DDL DDL - Data Definition Language:
 Statements used to define the database structure or
schema. Some examples:
 CREATE - to create objects in the database
 ALTER - alters the structure of the database
 DROP - delete objects from the database
 RENAME - rename an object

7. Schema Definition in SQL
 Create table : Example :
create table branch (branch-name char(15), branch-city
char(30),assets integer,
primary key (branch-name),
check (assets >= 0))
 Delete :
Delete table : drop table r
Delete tuples : Delete from r
 Alter table :
Add Attribute : alter table r add AD
Drop attribute : alter table r drop A

9. Data Manipulation Language
DML- Data Manipulation Language:
Statements used for managing data within
schema objects.
 SELECT - retrieve data from the a database
 INSERT - insert data into a table
 UPDATE - updates existing data within a table
 DELETE - deletes all records from a table, the
space for the records remain
 CALL - call a PL/SQL or Java subprogram

10. Example Setting Schema &
Attributes
 Branch-schema = (branch-name, branch-city,
assets)
 Customer-schema = (customer-name, customer-
street, customer-city)
 Loan-schema = (loan-number, branch-name,
amount)
 Borrower-schema = (customer-name, loan-number)
 Account-schema = (account-number, branch-name,
balance)
 Depositor-schema = (customer-name, account-
number)

11. Basic SQL Query
 Select Clause :
1. select branch-name from loan Retain Duplicates
2. select distinct branch-name from loan Remove
duplicates
3. select all branch-name from loan Retain Duplicates
 Where Clause :
1. select loan-number from loan where branch-name =
’Perryridge’ and amount > 1200
 From Clause :
select customer-name, borrower.loan-number, amount
from borrower, loan where borrower.loan-number =
loan.loan-number

12. Basic SQL Query
 Rename Operation :
select customer-name, borrower.loan-number as loan-id,
amount from borrower, loan where borrower.loan-
number = loan.loan-number
 Tuple variables :
select customer-name, T.loan-number, S.amount from
borrower as T, loan as S where T.loan-number = S.loan-
number
Tuple variables are most useful for comparing two tuples
in the same relation.
 String Operations :
select customer-name from customer where customer-
street like ’%Main%’

13. Basic SQL Query
 Ordering the Display of Tuples :
select distinct customer-name from borrower, loan where
borrower.loan-number = loan.loan-number and branch-
name = ’Perryridge’ order by customer-name
select * from loan order by amount desc, loan-number asc

14. Set Operations
 Union Operation : find all customers having a loan,
an account, or both
(select customer-name from depositor) union (select
customer-name from borrower) Removes Duplicates
 Intersect Operation : find all customers who have
both a loan and an account
(select distinct customer-name from depositor) intersect
(select distinct customer-name from borrower) Removes
Duplicates
 Except Operation : find all customers who have an
account but no loan
(select distinct customer-name from depositor) except
(select customer-name from borrower)

15. Aggregate Functions
avg, min, max, sum, count
Example : “Find the average balance for each customer
who lives in Harrison and has at least three accounts.”
select depositor.customer-name, avg (balance)
from depositor, account, customer
where depositor.account-number = account.account-
number and
depositor.customer-name = customer.customer-name and
customer-city = ’Harrison’
group by depositor.customer-name
having count (distinct depositor.account-number) >= 3

16. Nested Subqueries
 Set Membership : Example : find those customers
who are borrowers from the bank and who appear in
the list of account holders
select distinct customer-name from borrower where
customer-name in (select customer-name from
depositor)
 Set Comparison : Example : Find the names of all
branches that have assets greater than those of at least
one branch located in Brooklyn.
select branch-name from branch where assets > some
(select assets from branch where branch-city =
’Brooklyn’)
>some : greater than at least one member

17. Views
 Find for each branch the sum of the amounts of all the
loans at the branch.
create view branch-total-loan(branch-name, total-loan) as
select branch-name, sum(amount) from loan groupby
branch-name

18. Complex Queries
 Derived Relations : Example : “find the maximum
across all branches of the total balance at each branch.”
select max(tot-balance)
from (select branch-name, sum(balance) from account
group by branch-name)
as branch-total (branch-name, tot-balance)
 with Clause : Example : find accounts with the
maximum balance; if there are many accounts with the
same maximum balance, all of them are selected.
with max-balance (value) as
select max(balance) from account
select account-number from account, max-balance
where account.balance = max-balance.value

19. Modification of the Database
 Deletion :
delete from account where branch-name = ’Perryridge’
 Insertion :
insert into account (account-number, branch-name,
balance) values (’A-9732’, ’Perryridge’, 1200)
 Updates : Example : “Pay 5 percent interest on
accounts whose balance is greater than average”
update account set balance = balance * 1.05
where balance > select avg (balance) from account

20. Joined Relations

21. Joined Relations

22. Joined Relations

23. Joined Relations