The document discusses various concepts related to relational databases including:
- Primary keys uniquely identify rows in a table. Foreign keys match values in other tables' primary keys.
- Relational databases represent data using relations which have a schema and instances consisting of tuples.
- Relational algebra operations like selection, projection, join, etc. allow querying relational data.
Introduction to Relational algebra in DBMS - The relational algebra is explained with all the operations. Some of the examples from the textbook is also solved and explained.
These slides cover basic introduction to Relational Algebra which is a part of Relational Database Management System(RDBMS). The content includes basic RA symbols, operations with visualization.
chapter 5-Relational Algebra and calculus.pptMisganawAbeje1
The basic set of operations for the relational model is the relational algebra. These operations enable a user to specify basic retrieval requests as relational algebra expressions. The result of a retrieval is a new
relation, which may have been formed from one or more relations in database management system.
Introduction to Relational algebra in DBMS - The relational algebra is explained with all the operations. Some of the examples from the textbook is also solved and explained.
These slides cover basic introduction to Relational Algebra which is a part of Relational Database Management System(RDBMS). The content includes basic RA symbols, operations with visualization.
chapter 5-Relational Algebra and calculus.pptMisganawAbeje1
The basic set of operations for the relational model is the relational algebra. These operations enable a user to specify basic retrieval requests as relational algebra expressions. The result of a retrieval is a new
relation, which may have been formed from one or more relations in database management system.
General packet radio services (GPRS) is step to efficiently transport high-speed data over the current GSM and TDMA-based wireless network infrastructures.
Deployment of GPRS networks allows a variety of new applications ranging from mobile e-commerce to mobile corporate VPN access
Deployments of GPRS network has already taken place in several countries in Europe and the far east.
We have learnt that any computer system is made of hardware and software.
The hardware understands a language, which humans cannot understand. So we write programs in high-level language, which is easier for us to understand and remember.
These programs are then fed into a series of tools and OS components to get the desired code that can be used by the machine.
This is known as Language Processing System.
screen speculo is an android App. The main feature of App is to mirror screen between multiple android devices. In this App, the screen of main user’s device will be visible to all other devices. This App will provide two different modes to connect with multiple user. First mode is open mode which allows other users to connect with main user and main user can share screen and media. Second mode is moderated access mode which enable moderator to approve and reject other user’s request that means main user will have all the controls.
8085 Pin Diagram, Demultiplexing and Generation Of Control Signals
Index::
Introduction of 8085 microprocessor
Logic pinout of 8085 microprocessor
Demultiplexing
Generation of control signals
One pass assembler, Two pass assembler,
Advanced Assembler Directives
Index
------
One-pass assembler
Forward Reference
Two-pass assembler using variant-I
Two-pass assembler using variant-II
Advanced Assembler Directives
Design of two pass assembler
Classes, Objects and Method - Object Oriented Programming with JavaRadhika Talaviya
Class is template for an object and object is instance of a class.
When we create a class, we are creating a new data type. we can use this type to declare objects of that type.
A firewall is a network security system that monitors and controls the incoming and outgoing network traffic based on predetermined security rules. Packet filter is a hardware or software designed to block or allow transmission of packets based on criteria such as port, IP address, protocol.
Shopping At Mall without standing in Queue for Bill Payment by Scanning Bar c...Radhika Talaviya
Banking can be defined as the business activity of accepting and safeguarding money owned by other individual and entities, and then lending out this money in order to earn a profit. However, with the passage of time, the activities covered by banking business have widened and now various other services and also offered by banks. The banking services these day, include issuance of debit and credit card, providing safe custody of valuable items, lockers, ATM services and online transfer of fund across the country/world. We have chosen the topic which combine banking process and shopping system.
A total computer system include both hardware and software. Hardware consist of the physical components and all associated equipment.
Software refers to the programs that are written for the computer.
Writing a program for a computer consist of specifying, directly or indirectly, a sequence of machine instruction.
The 25 instruction of the basic computer are shown in Table-1. Each instruction is assigned a three-letter symbol to facilitate writing symbolic program.
The first seven instructions are memory-reference instructions and the other 18 are register-reference and input-output instructions.
A memory reference instruction has three parts: a mode bit, an operation code of three bit, and a12-bit address.
A stack is a linear data structure in which an element can be inserted or deleted only at one end of the list.
A stack works on the principle of last in first out and is also known as a Last-In-First-Out (LIFO) list.
A bunch of books is one of the common examples of stack. A new book to be added to the bunch is placed at the top and a book to be removed is also taken off from the top.
Therefore, in order to take out the book at the bottom, all the books above it need to be removed from the bunch.
The changes in the surface air temperature,reffered to as the global temperature, brought about by the enhanced green house effect, which is enduced by emmission of greenhouse gases into the air.
Here in my lens, I am throwing light on the life cycle of a girl's life. It starts from when a girl is born in a family extending on to her upbringing to her marriage and then to her pregnancy and delivery. After which, if a girl is born again, the same cycle repeats.
Nanophysics the physics of structures and artefacts with
dimensions in the nanometer range or of
phenomena occurring in nanoseconds. Nanoscience is the study of atoms, molecules and object whose size is of the nanometer scale (1-100nm).
I'm OK, You're OK, by Thomas A Harris MD, is one of the best selling self-help books ever published.It is a practical guide to Transactional Analysis as a method for solving problems in life.
ACEP Magazine edition 4th launched on 05.06.2024Rahul
This document provides information about the third edition of the magazine "Sthapatya" published by the Association of Civil Engineers (Practicing) Aurangabad. It includes messages from current and past presidents of ACEP, memories and photos from past ACEP events, information on life time achievement awards given by ACEP, and a technical article on concrete maintenance, repairs and strengthening. The document highlights activities of ACEP and provides a technical educational article for members.
Online aptitude test management system project report.pdfKamal Acharya
The purpose of on-line aptitude test system is to take online test in an efficient manner and no time wasting for checking the paper. The main objective of on-line aptitude test system is to efficiently evaluate the candidate thoroughly through a fully automated system that not only saves lot of time but also gives fast results. For students they give papers according to their convenience and time and there is no need of using extra thing like paper, pen etc. This can be used in educational institutions as well as in corporate world. Can be used anywhere any time as it is a web based application (user Location doesn’t matter). No restriction that examiner has to be present when the candidate takes the test.
Every time when lecturers/professors need to conduct examinations they have to sit down think about the questions and then create a whole new set of questions for each and every exam. In some cases the professor may want to give an open book online exam that is the student can take the exam any time anywhere, but the student might have to answer the questions in a limited time period. The professor may want to change the sequence of questions for every student. The problem that a student has is whenever a date for the exam is declared the student has to take it and there is no way he can take it at some other time. This project will create an interface for the examiner to create and store questions in a repository. It will also create an interface for the student to take examinations at his convenience and the questions and/or exams may be timed. Thereby creating an application which can be used by examiners and examinee’s simultaneously.
Examination System is very useful for Teachers/Professors. As in the teaching profession, you are responsible for writing question papers. In the conventional method, you write the question paper on paper, keep question papers separate from answers and all this information you have to keep in a locker to avoid unauthorized access. Using the Examination System you can create a question paper and everything will be written to a single exam file in encrypted format. You can set the General and Administrator password to avoid unauthorized access to your question paper. Every time you start the examination, the program shuffles all the questions and selects them randomly from the database, which reduces the chances of memorizing the questions.
TOP 10 B TECH COLLEGES IN JAIPUR 2024.pptxnikitacareer3
Looking for the best engineering colleges in Jaipur for 2024?
Check out our list of the top 10 B.Tech colleges to help you make the right choice for your future career!
1) MNIT
2) MANIPAL UNIV
3) LNMIIT
4) NIMS UNIV
5) JECRC
6) VIVEKANANDA GLOBAL UNIV
7) BIT JAIPUR
8) APEX UNIV
9) AMITY UNIV.
10) JNU
TO KNOW MORE ABOUT COLLEGES, FEES AND PLACEMENT, WATCH THE FULL VIDEO GIVEN BELOW ON "TOP 10 B TECH COLLEGES IN JAIPUR"
https://www.youtube.com/watch?v=vSNje0MBh7g
VISIT CAREER MANTRA PORTAL TO KNOW MORE ABOUT COLLEGES/UNIVERSITITES in Jaipur:
https://careermantra.net/colleges/3378/Jaipur/b-tech
Get all the information you need to plan your next steps in your medical career with Career Mantra!
https://careermantra.net/
NO1 Uk best vashikaran specialist in delhi vashikaran baba near me online vas...Amil Baba Dawood bangali
Contact with Dawood Bhai Just call on +92322-6382012 and we'll help you. We'll solve all your problems within 12 to 24 hours and with 101% guarantee and with astrology systematic. If you want to take any personal or professional advice then also you can call us on +92322-6382012 , ONLINE LOVE PROBLEM & Other all types of Daily Life Problem's.Then CALL or WHATSAPP us on +92322-6382012 and Get all these problems solutions here by Amil Baba DAWOOD BANGALI
#vashikaranspecialist #astrologer #palmistry #amliyaat #taweez #manpasandshadi #horoscope #spiritual #lovelife #lovespell #marriagespell#aamilbabainpakistan #amilbabainkarachi #powerfullblackmagicspell #kalajadumantarspecialist #realamilbaba #AmilbabainPakistan #astrologerincanada #astrologerindubai #lovespellsmaster #kalajaduspecialist #lovespellsthatwork #aamilbabainlahore#blackmagicformarriage #aamilbaba #kalajadu #kalailam #taweez #wazifaexpert #jadumantar #vashikaranspecialist #astrologer #palmistry #amliyaat #taweez #manpasandshadi #horoscope #spiritual #lovelife #lovespell #marriagespell#aamilbabainpakistan #amilbabainkarachi #powerfullblackmagicspell #kalajadumantarspecialist #realamilbaba #AmilbabainPakistan #astrologerincanada #astrologerindubai #lovespellsmaster #kalajaduspecialist #lovespellsthatwork #aamilbabainlahore #blackmagicforlove #blackmagicformarriage #aamilbaba #kalajadu #kalailam #taweez #wazifaexpert #jadumantar #vashikaranspecialist #astrologer #palmistry #amliyaat #taweez #manpasandshadi #horoscope #spiritual #lovelife #lovespell #marriagespell#aamilbabainpakistan #amilbabainkarachi #powerfullblackmagicspell #kalajadumantarspecialist #realamilbaba #AmilbabainPakistan #astrologerincanada #astrologerindubai #lovespellsmaster #kalajaduspecialist #lovespellsthatwork #aamilbabainlahore #Amilbabainuk #amilbabainspain #amilbabaindubai #Amilbabainnorway #amilbabainkrachi #amilbabainlahore #amilbabaingujranwalan #amilbabainislamabad
A review on techniques and modelling methodologies used for checking electrom...nooriasukmaningtyas
The proper function of the integrated circuit (IC) in an inhibiting electromagnetic environment has always been a serious concern throughout the decades of revolution in the world of electronics, from disjunct devices to today’s integrated circuit technology, where billions of transistors are combined on a single chip. The automotive industry and smart vehicles in particular, are confronting design issues such as being prone to electromagnetic interference (EMI). Electronic control devices calculate incorrect outputs because of EMI and sensors give misleading values which can prove fatal in case of automotives. In this paper, the authors have non exhaustively tried to review research work concerned with the investigation of EMI in ICs and prediction of this EMI using various modelling methodologies and measurement setups.
Literature Review Basics and Understanding Reference Management.pptxDr Ramhari Poudyal
Three-day training on academic research focuses on analytical tools at United Technical College, supported by the University Grant Commission, Nepal. 24-26 May 2024
2. Structure of relational databases
Primary key: Each row of a table is uniquely identified by a primary key
composed of one or more columns.
Candidate key: A column, or group of columns, that uniquely identifies a
row in a table is called a candidate key.
Foreign key: A column, or combination of columns, that matches the
primary key of another table is called a foreign key.
3. For each attribute there is a set of permitted values called Domain.
In other words we can say that A Domain D is a set of atomic
values.
Ex:
For our account table if we have 3 attributes as branch name,
account number and balance. Then for attribute branch name,
domain is set of all branch names.
Attributes & Domains
4. Let D1 denotes the set of all account numbers.
D2 denotes the set of all branch names.
D3 denotes the set of all balances.
So any row of account of table must consist of 3 tuple (V1, V2,V3)
Where,
V1 is an account number in the domain D1.
V2 is branch name in the domain D2.
V3 is a balance in the domain D3.
Therefore we can say account is a subset of D1×D2×D3.
5. To generalize we can say that,a table of n attributes must be
subset of D1×D2×D3…×Dn-1×Dn
We can say that a relation to be a subset of Cartesian product of a
list of domain which corresponds to our definition of table.
The main construct for representing data in the relation model is
a relation.
A relation consists of a relation schema and a relation instance.
The relation instance is a table and relation schema describes the
column heads for the table.
The schema specifies the relation name,the name of each field
and the domain of each field.
6. An instance of a relation is a set of tuples can also be referred as
records, in which each tuple has the same number of fields as the
relation schema.
Let us take an example of student relation.
The student table has following attributes
a) Sid: student id
b) Name: name of the student
c) Age: age of student
7. sid name age
S101 Rohit 20
S102 Parita 22
S103 sanjana 23
Attributes
Field
names
Tulpes
Hence, A relational database is a collection of relations with
distinct relation names. The relational database schema is
the collection of schemas for the relations in the database.
8. Domain Constraint
In the schema, every attribute is declared to have a type integer, float,
date, Boolean, string, etc.
An insertion request can violate the domain constraint.
DBMS can check if insertion violates domain constraint and reject the
insertion.
9. Key Constraint and Constraint on Null Values
A key constraint is a statement that a certain minimal subset as the fields
of a relation is a unique identifier for a tuple.
A set of fields that uniquely identifies a tuple according to a key
constraint is called a candidate key for the relation.
Another constraint on attribute specifies whether null values are or are
not permitted.
E.g. if every student tuple must have a valid, non-null value for the name
attribute, the name of student is constrained to be NOT NULL.
10. Entity Integrity Constraint
A primary key must not contain a null value, else it may not be
possible to identify some tuples.
• For Example, if more than one tuple has a null value in its primary
key, we may not be able to distinguish them .
11. Referential Integrity and Foreign Keys
The condition for a foreign key given below, specify a referential integrity
constraint between two relation schemas R1 and R2.
A set of attributes Fk in relation schema R1 is a foreign key of R1 that
references relation R2 if it satisfies following 2 rules.
1. The attributes in Fk have the same domain, as the primary key attribute
Pk of R2, the attributes Fk are said to reference to the relation R2.
2. A value of Fk in a tuple t1 in the current state r1(R1) either occur as a
value of Pk for some tuple t2 in the r2(R2) or is null.
12. In this definition R1 is called the referencing relation and R2 is
the referenced relation.
Sid Name Age
S101 Swati 20
S102 Ruchita 20
S103 Ushma 19
S104 Jones 25
Cid Grade Studid
His.111 A S101
Maths121 B S102
Topology1 B S103
Sci.11 C S104
Foreign Key Primary Key
Student
(Referenced relation)
Enrolled
(Referencing Relation)
13. Relational algebra
It is one of the two formal query languages associated with the relational
model.
Six basic operators are as below:
1. Selection
2. Projection
3. Union
4. Intersection
5. Set difference
6. Cross product
7. Renaming
The operators take one or two relations as inputs and produce a new relation
as a result.
15. Selection
The select operation selects tuples that satisfy a given predicate.
Notation: σc(r)
c is called the selection predicate.
c = <attribute> op <attribute> or <constant>
where, op is one of: <,<=,=,!=,>,>=.
Ex:
σ rating > 8(S2)
16. The selection criteria is rating > 8.
The result is shown in the below table.
Sid Sname rating Age
28 Swati 9 35
58 Uttam 10 35
17. Projection
The project operation is a unary operation that returns its argument
relation, with certain attributes left out.
Notation: П A1,A2…Ak (r)
where A1, A2 are attribute names and r is a relation name.
The result is defined as the relation of k columns obtained by erasing
the columns that are not listed.
Duplicate rows removed from result.
Ex:
П sname,rating(S2)
18. The result is shown in below table:
Sname rating
Swati 9
Sonal 8
Maulik 5
Uttam 10
19. Now, using selection &projection we can compute the names
and rating of highly rated sailor as:
П sname,rating(σ rating > 8(S2))
The result is obtained by applying the selection to S2 and then
applying the projection, which is as shown in below table.
Sname rating
Swati 9
Uttam 10
20. Union
In order to perform the union operation, both operand relations must be
union-compatible i.e. they must have same number of columns drawn
from the same domain.
R U S returns a relation instance containing all tuples that occur in either
relation instance R or relation instance S(or both).
Ex:
S1 U S2.
21. The union of S1 & S2. i.e.S1 U S2 would result in:
Sid Sname rating Age
22 Ritesh 7 45
31 Ritesh 8 55
58 Uttam 10 30
28 Swati 9 35
44 Maulik 5 35
22. Intersection
R ∩ S returns a relation instance containing all tuples that occur both
in R and S.
The relation R and S must be union compatible and the schema of
the result is defined to be identical to the schema of R.
Ex:
S1 ∩ S2.
Sid Sname rating Age
31 Ritesh 8 55
58 Uttam 10 30
23. Set difference
R – S returns a relation instance containing all tuples that occur in R
but not in S.
Ex:
S1 – S2
The set difference S1 – S2 is as shown in table.
Sid Sname rating Age
22 Ritesh 7 45
24. Cross product
R × S returns a relation instance whose schema contains all the field of
R followed by all the fields of S.
The cross product operation is also known as the Cartesian product.
Ex:
The cross product between two instance S1 and R1 which are as
shown in the next table:
26. R1 and S1 both have a field named sid .The cross product between
them is as shown in below table.
Sid Sname Rating Age Sid Bid Day
22 Ritesh 7 45 22 101 10/10/96
22 Ritesh 7 45 58 103 11/12/96
31 Sonal 8 55 22 101 10/10/96
31 Sonal 8 55 58 103 11/12/96
58 Uttam 10 35 22 101 10/10/96
58 Uttam 10 35 58 103 11/12/96
27. Renaming
The results of relational-algebra expressions do not have a
name that we can use to refer to them. Renaming is useful to
be able to give them names.
The rename operator is denoted by the lowercase Greek letter
rho (ρ).
Given a relational-algebra expression E, the expression ρx(E)
returns the result of expression E under the name x.
28. Join
Join operation is used to combine information from two or more
relations.
A join can be defined as a cross product followed by selections
and projections. The result of a cross product is much larger than
the result of a join.
There are several kind of joins:
• Condition join
• Equijoin
• Natural join
29. Defined as a cross-product followed by a selection:
R ⋈c S = σc(R S) where c is the condition.
Example:
Given the sample relational instances S1 and R1
The condition join S1 ⋈S1.sid<R1.sid R1 yields
Sid Sname Rating Age
22 Dustin 7 45.0
31 Lubber 8 55.5
58 Rusty 10 35.0
Sid Bid Day
22 101 10/10/96
58 103 11/12/96
Condition join
(sid) Sname Rating Age (sid) Bid Day
22 Dustin 7 45.0 58 103 11/12/96
31 Lubber 8 55.5 58 103 11/12/96
30. Equijoin
Special case of the condition join where the join condition consists solely
of equalities between two fields in R and S connected by the logical AND
operator (∧).
Example: Given the two sample relational instances S1 and R1
Sid Sname Rating Age
22 Dustin 7 45.0
31 Lubber 8 55.5
58 Rusty 10 35.0
Sid Bid Day
22 101 10/10/96
58 103 11/12/96
32. Natural join
Special case of equijoin where equalities are implicitly specified on
all fields having the same name in R and S.
The condition c is now left out, so that the “bow tie” operator by
itself signifies a natural join.
N. B. If the two relations have no attributes in common, the natural
join is simply the cross-product.
33. Division
The division operator is used for queries which involve the ‘all’ qualifier.
such as “Find the names of sailors who have reserved all boats”..
Consider two relation instances A and B in which A has two fields x and y
and B has just one field y , with the same domain as in A.
The division operator A/B is defined as the set of all x values that for every
y value in B, there is a tuple <x,y> in A.
An analogy with integer division may also help to understand division. For
integers A and B, A/B is the largest integer Q such that Q * B ≤ A.
For relation instances A and B , A/B in the largest relation instance Q such
that Q × B ⊆ A.
34. S# P#
S1 P1
S1 P2
S1 P3
S1 P4
S2 P1
S2 P2
S3 P2
S4 P2
S4 P4
P#
P2
P#
P2
P4
P#
P1
P2
P4
S#
S1
S2
S3
S4
S#
S1
S4
S#
S1
The relation A can be thought of as a relation listing parts supplied by
suppliers and of the B relations as listing parts. A/Bi computes
suppliers who supply all parts listed in relation instance Bi.
35. Generalized projection
The generalized projection extends the projection operation by allowing
arithmetic functions to be used in the projection list.
The generalized projection has the form
Where, E is any relational algebra expression. each of F1,
F2,…, Fn is an arithmetic expression involving constants and
attributes in the schema of E.
1 2, ,..., ( )nF F F E
36. Customer name Limit Credit balance
Swati 2000 1750
Ruchita 1500 1500
Manthan 6000 700
Ushma 2000 400
Customer name Result
Swati 250
Ruchita 5300
Manthan 1600
Ushma 0
Let us consider the following relation
Suppose if we want to find out how much each person can spend,
we can write: ,lim ( inf)customer name it creditbalance credit
37. Aggregate function
Aggregate function takes a collection of values and returns a single value
as a result.
Aggregate functions are sum, avg, count, min and max.
To understand aggregate function , lets us consider the pt-works relation
for part time employees.
Employee-name Branch-name Salary
Swati Pune 1500
Ruchita Pune 1300
Manthan Mumbai 5300
Ushma Mumbai 1500
Arpita Delhi 2500
Sameer Delhi 1300
38. Branch name Salary
Delhi 3800
Mumbai 6800
Pune 2800
To find out the total sum of salaries of all the part
employees in the bank. The expression would be
39. Outer join
This operation is an extension of the join operation of deal with missing
information.
These are three types of out joins:
a) Left outer join, denoted by
b) Right outer join, denoted by
c) Full outer join, denoted by
40. Consider the employee and ft-works relations.
Employee name Street City
Swati Salisbury park Pune
Ruchita Kothrud Mumbai
Ushma Sion Delhi
Arpit Mint street Chennai
Employee name Branch name Salary
Swati ABC 1500
Ruchita XYZ 1300
Ushma PQR 5300
Arpit WBC 1500
41. Employee ⋈ ft-works
Employee-name Street City Branch-name Salary
Swati Salisbury park Pune ABC 1500
Ruchita Kothrud Mumbai XYZ 1300
Ushma Sion Delhi PQR 5300
42. Employee-name Street City Branch-name Salary
Swati Salisbury park Pune ABC 1500
Ruchita Kothrud Mumbai XYZ 1300
Ushma Sion Delhi PQR 5300
Arpit Mint street Chennai Null Null
Left outer join takes all tuples in the left relation that didn’t match
with any tuple in right relation, pads the tuples with null values for all
other attributes from the right relation.
43. The right outer join is symmetric with left outer join. It pads
tuples from the right relation that did not match any from left
relation with nulls and adds them to the result of natural join.
Employee-name Street City Branch-name Salary
Swati Salisbury park Pune ABC 1500
Ruchita Kothrud Mumbai XYZ 1300
Ushma Sion Delhi PQR 5300
Arpita Null Null WBC 1500
44. Employee-name Street City Branch-name Salary
Swati Salisbury park Pune ABC 1500
Ruchita Kothrud Mumbai XYZ 1300
Ushma Sion Delhi PQR 5300
Arpit Mint street Chennai Null Null
Arpita Null Null WBC 1500
The full outer join does both of these operations, padding tuples
from the left relation that didn’t match any from the relation, as
well as tuples from the right relation that didn’t match any from the
left relation.
45. Example
sid Sname Rating Age
22 Swati 7 45
29 Ushma 1 33
31 Ruchita 8 55.5
32 Manthan 8 25.5
58 Amit 10 35
64 Arpit 3 63.5
Sid Bid Day
22 101 10/10/98
22 102 10/10/98
22 103 10/8/98
31 101 11/10/98
31 102 11/6/98
31 103 11/2/98
64 101 9/5/98
64 102 9/8/98
64 103 9/8/98
Bid bname Color
101 Marine Red
102 Clipper Green
103 Interlake Blue
46. a) Find the names of sailors who have reserved boats 103.
sname((σbid=103 Reserves) ⋈ Sailors)
b) Find the names of sailors who have reserved a red boat.
sname((σcolor=‘red’Boats) ⋈ Reserves ⋈ Sailors)
c) Find the names of sailors who have reserved at least one boat.
sname(Sailors ⋈ Reserves)
47. d) Find the names of sailors who have reserved a red or green boat.
(Tempboats, (σcolor=‘red’Boats) ∪ (σcolor=‘green’Boats))
sname(Tempboats ⋈ Reserves ⋈ Sailors)
e) Find the names of sailors who have reserved all boats called
Interlake.
(Tempsids, (sid,bidReserves)/(bid(σbname=‘Interlake’Boats)))
sname(Tempsids ⋈ Sailors)
48. f) Find the sids of sailors with age over 20 who have not
reserved a red boat.
sid(σage>20Sailors) - sid((σcolor=‘red’Boats) ⋈ Reserves ⋈ Sailors)
g) Find the colors of boats reserved by Lubber.
color((σsname=‘Lubber’Sailors)Sailors ⋈ Reserves ⋈ Boats)