Unit04 dbms

[object Object],[object Object]

[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

History ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Data Definition Language ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Allows the specification of:

Create Table Construct ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Domain Types in SQL ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Integrity Constraints on Tables ,[object Object],[object Object],Example: Declare branch_name as the primary key for branch . create table branch ( branch_name char(15) , branch_city char(30) not null , assets integer, primary key ( branch_name )) primary key declaration on an attribute automatically ensures not null in SQL-92 onwards, needs to be explicitly stated in SQL-89

Basic Insertion and Deletion of Tuples ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Drop and Alter Table Constructs ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Basic Query Structure ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

The select Clause ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

The select Clause (Cont.) ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

The select Clause (Cont.) ,[object Object],[object Object],[object Object],[object Object],[object Object]

The where Clause ,[object Object],[object Object],[object Object],[object Object],[object Object]

The from Clause ,[object Object],[object Object],[object Object],[object Object],[object Object],select customer_name, borrower.loan_number, amount from borrower, loan where borrower.loan_number = loan.loan_number and branch_name = 'Perryridge'

The Rename Operation ,[object Object],[object Object],[object Object],select customer_name, borrower.loan_number as loan_id, amount from borrower, loan where borrower.loan_number = loan.loan_number

Tuple Variables ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],select customer_name, T.loan_number, S.amount from borrower as T, loan as S where T.loan_number = S.loan_number

Example Instances ,[object Object],[object Object],R1 S1 S2

Basic SQL Query ,[object Object],[object Object],[object Object],[object Object],SELECT [DISTINCT] target-list FROM relation-list WHERE qualification

Conceptual Evaluation Strategy ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Example of Conceptual Evaluation SELECT S.sname FROM Sailors S, Reserves R WHERE S.sid=R.sid AND R.bid=103

A Note on Range Variables ,[object Object],SELECT S.sname FROM Sailors S, Reserves R WHERE S.sid=R.sid AND bid=103 SELECT sname FROM Sailors, Reserves WHERE Sailors.sid=Reserves.sid AND bid=103 It is good style, however, to use range variables always! OR

Find sailors who’ve reserved at least one boat ,[object Object],[object Object],SELECT S.sid FROM Sailors S, Reserves R WHERE S.sid=R.sid

Expressions and Strings ,[object Object],[object Object],[object Object],SELECT S.age, age1=S.age-5, 2*S.age AS age2 FROM Sailors S WHERE S.sname LIKE ‘B_%B’

String Operations ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Ordering the Display of Tuples ,[object Object],[object Object],[object Object],[object Object]

Duplicates ,[object Object],[object Object],[object Object],[object Object],[object Object]

Duplicates (Cont.) ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Set Operations ,[object Object],[object Object],[object Object],[object Object],[object Object]

Set Operations ,[object Object],( select customer_name from depositor ) except (select customer_name from borrower) ( select customer_name from depositor ) intersect (select customer_name from borrower) ,[object Object],(select customer_name from depositor ) union (select customer_name from borrower) ,[object Object]

Find sid’s of sailors who’ve reserved a red or a green boat ,[object Object],[object Object],[object Object],SELECT S.sid FROM Sailors S, Boats B, Reserves R WHERE S.sid=R.sid AND R.bid=B.bid AND (B.color=‘red’ OR B.color=‘green’) SELECT S.sid FROM Sailors S, Boats B, Reserves R WHERE S.sid=R.sid AND R.bid=B.bid AND B.color=‘red’ UNION SELECT S.sid FROM Sailors S, Boats B, Reserves R WHERE S.sid=R.sid AND R.bid=B.bid AND B.color=‘green’

Find sid’s of sailors who’ve reserved a red and a green boat ,[object Object],[object Object],[object Object],SELECT S.sid FROM Sailors S, Boats B1, Reserves R1, Boats B2, Reserves R2 WHERE S.sid=R1.sid AND R1.bid=B1.bid AND S.sid=R2.sid AND R2.bid=B2.bid AND (B1.color=‘red’ AND B2.color=‘green’) SELECT S.sid FROM Sailors S, Boats B, Reserves R WHERE S.sid=R.sid AND R.bid=B.bid AND B.color=‘red’ INTERSECT SELECT S.sid FROM Sailors S, Boats B, Reserves R WHERE S.sid=R.sid AND R.bid=B.bid AND B.color=‘green’ Key field!

Nested Queries ,[object Object],[object Object],[object Object],SELECT S.sname FROM Sailors S WHERE S.sid IN ( SELECT R.sid FROM Reserves R WHERE R.bid=103) Find names of sailors who’ve reserved boat #103:

Nested Queries with Correlation ,[object Object],[object Object],[object Object],SELECT S.sname FROM Sailors S WHERE EXISTS ( SELECT * FROM Reserves R WHERE R.bid=103 AND S.sid =R.sid) Find names of sailors who’ve reserved boat #103:

Aggregate Functions ,[object Object],[object Object]

Aggregate Functions (Cont.) ,[object Object],[object Object],[object Object],select avg (balance) from account where branch_name = 'Perryridge' select count (*) from customer select count (distinct customer_name) from depositor

Aggregate Functions – Group By ,[object Object],Note: Attributes in select clause outside of aggregate functions must appear in group by list select branch_name, count (distinct customer_name) from depositor, account where depositor.account_number = account.account_number group by branch_name

Aggregate Functions – Having Clause ,[object Object],Note: predicates in the having clause are applied after the formation of groups whereas predicates in the where clause are applied before forming groups select branch_name, avg ( balance ) from account group by branch_name having avg ( balance ) > 1200

Nested Subqueries ,[object Object],[object Object],[object Object]

“In” Construct ,[object Object],[object Object],select distinct customer_name from borrower where customer_name not in ( select customer_name from depositor ) select distinct customer_name from borrower where customer_name in ( select customer_name from depositor )

Example Query ,[object Object],[object Object],select distinct customer_name from borrower, loan where borrower.loan_number = loan.loan_number and branch_name = 'Perryridge' and ( branch_name, customer_name ) in (select branch_name, customer_name from depositor, account where depositor.account_number = account.account_number )

“Some” Construct ,[object Object],[object Object],select branch_name from branch where assets > some (select assets from branch where branch_city = ' Brooklyn ' ) select distinct T.branch_name from branch as T, branch as S where T.assets > S.assets and S.branch_city = ' Brooklyn '

“All” Construct ,[object Object],select branch_name from branch where assets > all (select assets from branch where branch_city = 'Brooklyn')

“Exists” Construct ,[object Object],select distinct S.customer_name from depositor as S where not exists ( ( select branch_name from branch where branch_city = 'Brooklyn') except ( select R.branch_name from depositor as T, account as R where T.account_number = R.account_number and S.customer_name = T.customer_name )) ,[object Object],[object Object]

Absence of Duplicate Tuples ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Example Query ,[object Object],select distinct T.customer_name from depositor as T where not unique ( select R.customer_name from account, depositor as R where T.customer_name = R.customer_name and R.account_number = account.account_number and account.branch_name = ' Perryridge ' ) ,[object Object]

Modification of the Database – Deletion ,[object Object],[object Object],[object Object],[object Object]

Example Query ,[object Object],delete from account where balance < ( select avg ( balance ) from account ) ,[object Object],[object Object],[object Object],[object Object]

Modification of the Database – Insertion ,[object Object],[object Object],[object Object],[object Object],[object Object]

Modification of the Database – Insertion ,[object Object],[object Object],[object Object],[object Object]

Modification of the Database – Updates ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Case Statement for Conditional Updates ,[object Object],[object Object]

More on Set-Comparison Operators ,[object Object],[object Object],[object Object],SELECT * FROM Sailors S WHERE S.rating > ANY ( SELECT S2.rating FROM Sailors S2 WHERE S2.sname=‘Horatio’)

Rewriting INTERSECT Queries Using IN ,[object Object],[object Object],Find sid’s of sailors who’ve reserved both a red and a green boat: SELECT S.sid FROM Sailors S, Boats B, Reserves R WHERE S.sid=R.sid AND R.bid=B.bid AND B.color=‘red’ AND S.sid IN ( SELECT S2.sid FROM Sailors S2, Boats B2, Reserves R2 WHERE S2.sid=R2.sid AND R2.bid=B2.bid AND B2.color=‘green’)

Division in SQL ,[object Object],SELECT S.sname FROM Sailors S WHERE NOT EXISTS (( SELECT B.bid FROM Boats B) EXCEPT ( SELECT R.bid FROM Reserves R WHERE R.sid=S.sid)) SELECT S.sname FROM Sailors S WHERE NOT EXISTS ( SELECT B.bid FROM Boats B WHERE NOT EXISTS ( SELECT R.bid FROM Reserves R WHERE R.bid=B.bid AND R.sid=S.sid)) Sailors S such that ... there is no boat B without ... a Reserves tuple showing S reserved B Find sailors who’ve reserved all boats. (1) (2)

Aggregate Operators ,[object Object],COUNT (*) COUNT ( [ DISTINCT ] A) SUM ( [ DISTINCT ] A) AVG ( [ DISTINCT ] A) MAX (A) MIN (A) SELECT AVG (S.age) FROM Sailors S WHERE S.rating=10 SELECT COUNT (*) FROM Sailors S SELECT AVG ( DISTINCT S.age) FROM Sailors S WHERE S.rating=10 SELECT S.sname FROM Sailors S WHERE S.rating= ( SELECT MAX (S2.rating) FROM Sailors S2) single column SELECT COUNT ( DISTINCT S.rating) FROM Sailors S WHERE S.sname=‘Bob’

Find name and age of the oldest sailor(s) ,[object Object],[object Object],SELECT S.sname, MAX (S.age) FROM Sailors S SELECT S.sname, S.age FROM Sailors S WHERE S.age = ( SELECT MAX (S2.age) FROM Sailors S2) SELECT S.sname, S.age FROM Sailors S WHERE ( SELECT MAX (S2.age) FROM Sailors S2) = S.age

Motivation for Grouping ,[object Object],[object Object],[object Object],[object Object],SELECT MIN (S.age) FROM Sailors S WHERE S.rating = i For i = 1, 2, ... , 10:

Queries With GROUP BY and HAVING ,[object Object],[object Object],SELECT [DISTINCT] target-list FROM relation-list WHERE qualification GROUP BY grouping-list HAVING group-qualification

Conceptual Evaluation ,[object Object],[object Object],[object Object],[object Object]

Find age of the youngest sailor with age 18, for each rating with at least 2 such sailors SELECT S.rating, MIN (S.age) AS minage FROM Sailors S WHERE S.age >= 18 GROUP BY S.rating HAVING COUNT (*) > 1 Answer relation: Sailors instance:

Find age of the youngest sailor with age 18, for each rating with at least 2 such sailors.

Find age of the youngest sailor with age 18, for each rating with at least 2 such sailors and with every sailor under 60. HAVING COUNT (*) > 1 AND EVERY (S.age <=60) What is the result of changing EVERY to ANY?

Find age of the youngest sailor with age 18, for each rating with at least 2 sailors between 18 and 60. SELECT S.rating, MIN (S.age) AS minage FROM Sailors S WHERE S.age >= 18 AND S.age <= 60 GROUP BY S.rating HAVING COUNT (*) > 1 Answer relation: Sailors instance:

For each red boat, find the number of reservations for this boat ,[object Object],[object Object],[object Object],SELECT B.bid, COUNT (*) AS scount FROM Sailors S, Boats B, Reserves R WHERE S.sid=R.sid AND R.bid=B.bid AND B.color=‘red’ GROUP BY B.bid

Find age of the youngest sailor with age > 18, for each rating with at least 2 sailors (of any age) ,[object Object],[object Object],[object Object],[object Object],SELECT S.rating , MIN (S.age) FROM Sailors S WHERE S.age > 18 GROUP BY S.rating HAVING 1 < ( SELECT COUNT (*) FROM Sailors S2 WHERE S.rating=S2.rating )

Find those ratings for which the average age is the minimum over all ratings ,[object Object],SELECT S.rating FROM Sailors S WHERE S.age = ( SELECT MIN ( AVG (S2.age)) FROM Sailors S2) SELECT Temp.rating, Temp.avgage FROM ( SELECT S.rating, AVG (S.age) AS avgage FROM Sailors S GROUP BY S.rating) AS Temp WHERE Temp.avgage = ( SELECT MIN (Temp.avgage) FROM Temp) ,[object Object]

Null Values ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Null Values ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Null Values and Three Valued Logic ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Null Values and Aggregates ,[object Object],[object Object],[object Object],[object Object],[object Object]

Joined Relations** ,[object Object],[object Object],[object Object],[object Object]

Joined Relations – Datasets for Examples ,[object Object],[object Object],[object Object]

Joined Relations – Examples ,[object Object],[object Object]

Joined Relations – Examples ,[object Object],[object Object],[object Object],select customer_name from ( depositor natural full outer join borrower ) where account_number is null or loan_number is null

Joined Relations – Examples ,[object Object],[object Object],[object Object],[object Object]

Derived Relations ,[object Object],[object Object],[object Object],[object Object]

Integrity Constraints (Review) ,[object Object],[object Object],[object Object],[object Object],[object Object]

General Constraints ,[object Object],[object Object],[object Object],CREATE TABLE Sailors ( sid INTEGER, sname CHAR(10), rating INTEGER, age REAL, PRIMARY KEY (sid), CHECK ( rating >= 1 AND rating <= 10 ) CREATE TABLE Reserves ( sname CHAR(10), bid INTEGER, day DATE, PRIMARY KEY (bid,day), CONSTRAINT noInterlakeRes CHECK (`Interlake’ <> ( SELECT B.bname FROM Boats B WHERE B.bid=bid)))

Constraints Over Multiple Relations ,[object Object],[object Object],[object Object],CREATE TABLE Sailors ( sid INTEGER, sname CHAR(10), rating INTEGER, age REAL, PRIMARY KEY (sid), CHECK ( (SELECT COUNT (S.sid) FROM Sailors S) + (SELECT COUNT (B.bid) FROM Boats B) < 100 ) CREATE ASSERTION smallClub CHECK ( (SELECT COUNT (S.sid) FROM Sailors S) + (SELECT COUNT (B.bid) FROM Boats B) < 100 ) Number of boats plus number of sailors is < 100

Triggers ,[object Object],[object Object],[object Object],[object Object],[object Object]

Triggers: Example (SQL:1999) ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Unit04 dbms

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