Database 2020

DATABASE
‫البيانات‬ ‫قواعد‬ ‫محور‬
By Eng. Joud Khattab2020

Content
■ Overview.
■ Entity Relational Model.
■ Relational Model.
■ SQL.
■ XML.
■ Normalization.
■ Rational Algebra.
■ MCQ.
2020 By Eng. Joud Khattab

OVERVIEW

Definitions (‫)تعاريف‬
■‫المعطيات‬ ‫قاعدة‬( :Database)
–،‫المتكررة‬ ‫غير‬ ‫المهيكلة‬ ‫المعطيات‬ ‫من‬ ‫مجموعة‬
–‫تطبيقي‬ ‫برامج‬ ‫عدة‬ ‫قبل‬ ‫من‬ ‫إليها‬ ‫بالوصول‬ ‫يسمح‬ ‫تخزين‬ ‫وسط‬ ‫على‬ ‫المسجلة‬‫ة‬.
■‫المعطيات‬ ‫قواعد‬ ‫إدارة‬ ‫نظام‬( :DBMS: Data Base Management Systems)
–،‫بينها‬ ‫فيما‬ ‫المرتبطة‬ ‫المعطيات‬ ‫من‬ ‫تجمع‬
–‫المعطيات‬ ‫هذه‬ ‫إلى‬ ‫الوصول‬ ‫توفر‬ ‫التي‬ ‫البرامج‬ ‫من‬ ‫ومجموعة‬.
■‫المعطيات‬ ‫قواعد‬ ‫إدارة‬ ‫نظم‬ ‫أهداف‬:
–‫المعطيات‬ ‫واسترجاع‬ ‫تخزين‬ ‫من‬ ‫يمكن‬ ‫وفعال‬ ‫مالئم‬ ‫عمل‬ ‫محيط‬ ‫توفير‬.
–‫التقليدية‬ ‫المعطيات‬ ‫وإدارة‬ ‫تخزين‬ ‫نظم‬ ‫مساوئ‬ ‫على‬ ‫التغلب‬(‫الملفات‬ ‫نظام‬.)

Database Applications
(‫المعطيات‬ ‫قواعد‬ ‫)تطبيقات‬
■‫الطالب‬ ‫شؤون‬(Universities:)‫العالمات‬ ،‫المواد‬ ،‫التسجيل‬.
■‫البشرية‬ ‫الموارد‬(Human resources:)‫الضرائب‬ ،‫الرواتب‬ ،‫الموظفين‬ ‫سجالت‬.
■‫المبيعات‬(Sales:)‫والمشتريات‬ ‫والمنتجات‬ ‫الزبائن‬
■‫التصنيع‬(Manufacturing:)‫التوريد‬ ،‫الطلبات‬ ،‫التخزين‬ ،‫اإلنتاج‬.
■‫الجوية‬ ‫الخطوط‬(Airlines:)‫الرحالت‬ ‫وتنظيم‬ ‫الحجز‬.
■‫المصارف‬(Banking:)‫المصرفية‬ ‫المعامالت‬.

Database Problems
(‫المعطيات‬ ‫قواعد‬ ‫)مشاكل‬
■‫المعطيات‬ ‫وتضارب‬ ‫تكرار‬:
–‫ملف‬ ‫من‬ ‫أكثر‬ ‫في‬ ‫المعلومات‬ ‫لنفس‬ ‫تكرار‬ ،‫للملفات‬ ‫مختلفة‬ ‫وأشكال‬ ‫بنى‬.
■‫المعطيات‬ ‫إلى‬ ‫الوصول‬ ‫صعوبة‬:
–‫المختلفة‬ ‫االستفسارات‬ ‫لمعالجة‬ ‫جديدة‬ ‫برامج‬ ‫لكتابة‬ ‫الحاجة‬.
■‫المعطيات‬ ‫تكامل‬ ‫عدم‬:
–‫الموجو‬ ‫الشروط‬ ‫في‬ ‫التغيير‬ ‫أو‬ ‫جديدة‬ ‫شروط‬ ‫إضافة‬ ‫الصعب‬ ‫ومن‬ ‫البرامج‬ ‫ضمن‬ ‫مكتوبة‬ ‫تكون‬ ‫المعطيات‬ ‫على‬ ‫الشروط‬‫دة‬.
–‫مختلفة‬ ‫ملفات‬ ‫في‬ ‫موجودة‬ ‫معطيات‬ ‫بعناصر‬ ‫الشرط‬ ‫يتعلق‬ ‫عندما‬ ‫الصعوبة‬ ‫تزداد‬.
■‫التعديالت‬ ‫تجزئة‬:
–‫جزئية‬ ‫تعديالت‬ ‫لتنفيذ‬ ‫نتيجة‬ ‫صحيحة‬ ‫وغير‬ ‫مستقرة‬ ‫غير‬ ‫بحالة‬ ‫القاعدة‬ ‫تترك‬ ‫أن‬ ‫لألعطال‬ ‫يمكن‬.
■‫المتزامن‬ ‫بالوصول‬ ‫التحكم‬ ‫صعوبة‬:
–‫أخطاء‬ ‫إلى‬ ‫يؤدي‬ ‫أن‬ ‫به‬ ‫المتحكم‬ ‫غير‬ ‫المتزامن‬ ‫للوصول‬ ‫يمكن‬.
–‫مثال‬:‫الوقت‬ ‫نفس‬ ‫في‬ ‫مستخدمين‬ ‫قبل‬ ‫من‬ ‫رصيد‬ ‫وتعديل‬ ‫قراءة‬.
■‫المعلومات‬ ‫أمن‬ ‫تطبيق‬ ‫صعوبة‬.

DBMS Functions
(‫المعطيات‬ ‫قواعد‬ ‫إدارة‬ ‫أنظمة‬ ‫)وظائف‬
■‫المعلومات‬ ‫مركزية‬.
■‫المعطيات‬ ‫استقالل‬.
■‫إجرائية‬ ‫غير‬ ‫لغات‬ ‫بواسطة‬ ‫المعطيات‬ ‫معالجة‬.
■‫المعطيات‬ ‫بإدارة‬ ‫الخاصة‬ ‫التسهيالت‬.
■‫بفعالية‬ ‫المعطيات‬ ‫إلى‬ ‫الوصول‬.
■‫المعطيات‬ ‫تكرار‬ ‫في‬ ‫التحكم‬.
■‫المعطيات‬ ‫تكامل‬.
■‫المعطيات‬ ‫تقسيم‬.
■‫المعطيات‬ ‫أمن‬ ‫توفير‬.

Database Structure
(‫المعطيات‬ ‫قواعد‬ ‫)بنية‬
■‫مركزية‬(Centralized)
■‫مخدم‬ ‫زبون‬(Client Server)
■‫تفرعيه‬(Parallel)
■‫موزعة‬(Distributed Database)

Applications Architecture
(‫التطبيقات‬ ‫)بنية‬
■‫طريق‬ ‫عن‬ ‫المعطيات‬ ‫قاعدة‬ ‫مع‬ ‫التطبيقية‬ ‫البرامج‬ ‫تتصل‬:
–‫تعليمات‬ ‫وجود‬ ‫تقبل‬ ‫البرمجة‬ ‫للغة‬ ‫توسيعات‬(SQL)
–‫برمجية‬ ‫تخاطب‬ ‫واجهة‬(API.)

Database Levels
(‫التجريد‬ ‫)مستويات‬
■‫المفاهيمي‬ ‫المستوى‬:‫واالرتباطات‬ ‫الكيانات‬ ‫مخططات‬ ‫مثل‬(ERD)
■‫المنطقي‬ ‫المستوى‬:‫النموذج‬ ‫مثل‬‫العالقاتي‬
■‫الفيزيائي‬ ‫المستوى‬.

ENTITY RELATIONSHIP
MODEL
‫االرتباطات‬ ‫و‬ ‫الكيانات‬ ‫نموذج‬

Entity Relationship Model
(‫االرتباطات‬ ‫و‬ ‫الكيانات‬ ‫)نموذج‬
■‫الكيانات‬ ‫هذه‬ ‫بين‬ ‫فيما‬ ‫واالرتباطات‬ ‫الكيانات‬ ‫من‬ ‫مجموعة‬ ‫هي‬ ‫المعطيات‬ ‫قاعدة‬
■‫الكيان‬( :entity)
–‫قاعدة‬ ‫في‬ ‫تخزينها‬ ‫سيجري‬ ‫التي‬ ‫األغراض‬ ‫من‬ ‫غيره‬ ‫عن‬ ‫ومميز‬ ‫موجود‬ ‫غرض‬
‫المعطيات‬:‫المدرس‬ ‫وكيان‬ ‫الطالب‬ ‫كيان‬ ‫مثل‬
–‫واصفات‬ ‫له‬ ‫الكيان‬(attributes:)‫وعنوان‬ ‫اسم‬ ‫شخص‬ ‫لكل‬ ‫مثال‬
–‫رئيسي‬ ‫مفتاح‬ ‫له‬ ‫الكيان‬(primary key)
■‫االرتباط‬( :relationship)
–‫أكثر‬ ‫أو‬ ‫كيانين‬ ‫بين‬ ‫اقتران‬ ‫هو‬.
–‫المدرس‬ ‫مع‬ ‫الطالب‬ ‫ارتباط‬ ‫مثل‬.
–‫واصفات‬ ‫له‬ ‫تكون‬ ‫أن‬ ‫يمكن‬ ً‫أيضا‬ ‫االرتباط‬.

■‫الواصفات‬ ‫أنواع‬:
–‫البسيطة‬ ‫الوصفات‬(simple:)‫الراتب‬ ،‫الكنية‬ ،‫االسم‬ ‫مثل‬.
–‫المركبة‬ ‫الواصفات‬(composite:)‫العنوان‬ ،‫الثالثي‬ ‫االسم‬ ‫مثل‬.
–‫القيم‬ ‫المتعددة‬ ‫الواصفات‬(multivalued:)‫الهاتف‬ ‫أرقام‬ ‫مثل‬.
–‫المشتقة‬ ‫الواصفات‬(derived:)‫الراتب‬ ،‫العمر‬ ‫مثل‬ ‫أخرى‬ ‫واصفات‬ ‫من‬ ‫حسابها‬ ‫يتم‬
‫السنوي‬.

■‫االرتباطات‬ ‫أنواع‬:
–‫االرتباط‬ ‫درجة‬:‫المرتبطة‬ ‫الكيانات‬ ‫عدد‬
■‫رباعية‬ ،‫ثالثية‬ ‫تكون‬ ‫أن‬ ‫يمكن‬ ‫لكن‬ ‫ثنائية‬ ‫االرتباطات‬ ‫معظم‬.
■‫ثالثية‬ ‫عالقة‬ ‫عن‬ ‫مثال‬:‫مشرف‬ ‫مدرس‬ ‫مع‬ ‫مشروع‬ ‫مع‬ ‫طالب‬ ‫عالقة‬.
–‫لالرتباط‬ ‫العددية‬ ‫القيود‬:
■‫لواحد‬ ‫واحد‬(One to one)
■‫لعدة‬ ‫واحد‬(One to many)
■‫لواحد‬ ‫عدة‬(Many to one)
■‫لعدة‬ ‫عدة‬(Many to many)
–‫المشاركة‬ ‫قيود‬:
■‫كاملة‬ ‫مشاركة‬(‫إجبارية‬ ‫عالقة‬)
■‫جزئية‬ ‫مشاركة‬(‫اختيارية‬ ‫عالقة‬)

■‫المفاتيح‬:
–‫الرئيسي‬ ‫المفتاح‬ ‫أو‬ ‫األعلى‬ ‫المفتاح‬(super key)
■‫الكيانات‬ ‫مجموعة‬ ‫من‬ ‫واحد‬ ‫كيان‬ ‫بتمييز‬ ‫متجمعة‬ ‫تسمح‬ ‫اكثر‬ ‫او‬ ‫واصفا‬ ‫تضم‬ ‫مجموعة‬
‫واحد‬ ‫صف‬ ‫الى‬ ‫المنتمية‬.
–‫المرشح‬ ‫المفتاح‬(candidate key)
■‫هذه‬ ‫من‬ ‫جزئية‬ ‫مجموعة‬ ‫توجد‬ ‫وال‬ ‫الواصفات‬ ‫من‬ ‫مجموعة‬ ‫من‬ ‫مؤلف‬ ‫رئيسي‬ ‫مفتاح‬
‫رئيسيا‬ ‫مفتاحا‬ ‫تكون‬ ‫المجموعة‬.
–‫األولي‬ ‫المفتاح‬(primary key)
■‫البعض‬ ‫بعضها‬ ‫عن‬ ‫الكيانات‬ ‫لتمييز‬ ‫أساسية‬ ‫كطريقة‬ ‫المصمم‬ ‫اختاره‬ ‫مرشح‬ ‫مفتاح‬
‫واحد‬ ‫كيانات‬ ‫صف‬ ‫الى‬ ‫والمنتمية‬.

■ A software release can be identified either by:
– major/minor version or by the date.
■ (year, major, minor) or (year, month, date, major)
– are super keys (since they are unique)
– but not candidate keys, (since you can remove year or major and the remaining
set will still be a super key)
■ (year, month, date) and (major, minor)
– are candidate keys, since you cannot remove any of the fields from them
without breaking uniqueness.
Year Month Date Major Minor
2008 01 13 0 1
2008 04 23 0 2
2009 11 05 1 0
2010 04 05 1 1

Entity Relationship Diagram (ERD)
( ‫كيان‬ ‫مخطط‬-‫ارتباط‬ )
One to One One to Many
Many to Many

■‫الواصفات‬ ‫من‬ ‫المختلفة‬ ‫األنواع‬ ‫تمثيل‬:

■‫الضعيف‬ ‫الكيان‬(weak entity)
–‫اولي‬ ‫مفتاح‬ ‫له‬ ‫ليس‬(primary key)‫عناصره‬ ‫بين‬ ‫يميز‬.
–‫المحدد‬ ‫الكيان‬ ‫أو‬ ‫القوي‬ ‫الكيان‬ ‫يسمى‬ ‫آخر‬ ‫كيان‬ ‫بوجود‬ ‫مرهون‬ ‫وجوده‬.
–‫التحديد‬ ‫عالقة‬ ‫تسمى‬ ‫إجبارية‬ ‫لواحد‬ ‫عدة‬ ‫بعالقة‬ ‫القوي‬ ‫الكيان‬ ‫مع‬ ‫يرتبط‬.
–‫الواحد‬ ‫القوي‬ ‫الكيان‬ ‫ضمن‬ ‫عناصره‬ ‫بين‬ ‫يميز‬ ‫مميز‬ ‫له‬.
–‫القو‬ ‫للكيان‬ ‫الرئيسي‬ ‫والمفتاح‬ ‫المميز‬ ‫من‬ ً‫مؤلفا‬ ‫الرئيسي‬ ‫مفتاحه‬ ‫يصبح‬‫المرتبط‬ ‫ي‬
‫به‬.

RELATIONAL MODEL
‫النموذج‬‫العالقاتي‬

FROM ERD TO
RELATIONAL MODEL
‫النموذج‬ ‫إلى‬ ‫واالرتباطات‬ ‫الكيانات‬ ‫نموذج‬ ‫من‬ ‫التحويل‬‫العالقاتي‬

From ERD to Relational model
■‫البسيطة‬ ‫الواصفات‬ ‫ذات‬ ‫القوية‬ ‫الكيانات‬ ‫تحويل‬:
–‫نفسه‬ ‫الرئيسي‬ ‫والمفتاح‬ ‫نفسها‬ ‫الواصفات‬ ‫لها‬ ‫عالقة‬ ‫إلى‬ ‫الكيان‬ ‫يتحول‬.
■‫الضعيفة‬ ‫الكيانات‬ ‫تحويل‬:
–،‫نفسها‬ ‫الواصفات‬ ‫لها‬ ‫عالقة‬ ‫إلى‬ ‫الضعيف‬ ‫الكيان‬ ‫يتحول‬
–،‫له‬ ‫المحدد‬ ‫القوي‬ ‫للكيان‬ ‫الرئيسي‬ ‫المفتاح‬ ‫واصفات‬ ‫إلى‬ ً‫ة‬‫إضاف‬
–،‫للعالقة‬ ً‫رئيسيا‬ ً‫مفتاحا‬ ‫المميزة‬ ‫الواصفات‬ ‫مع‬ ‫تصبح‬ ‫التي‬
–‫الكيانين‬ ‫بين‬ ‫االرتباط‬ ‫يمثل‬ ً‫خارجيا‬ ً‫مفتاحا‬ ‫وتكون‬.

From ERD to Relational model
■‫لواحد‬ ‫واحد‬ ‫الروابط‬( :one-to-one)
–‫ال‬ ‫أحد‬ ‫في‬ ‫الموجود‬ ‫الكيان‬ ‫عن‬ ‫الناتجة‬ ‫للعالقة‬ ‫الرئيسي‬ ‫المفتاح‬ ‫إضافة‬ ‫يمكن‬‫طرفين‬
ً‫خارجيا‬ ً‫مفتاحا‬ ‫ليصبح‬ ‫اآلخر‬ ‫الطرف‬ ‫في‬ ‫الموجود‬ ‫الكيان‬ ‫عن‬ ‫الناتجة‬ ‫العالقة‬ ‫إلى‬‫فيها‬.
■‫لعدة‬ ‫واحد‬ ‫الروابط‬( :one-to-many)
–‫الطر‬ ‫في‬ ‫الموجود‬ ‫الكيان‬ ‫عن‬ ‫الناتجة‬ ‫للعالقة‬ ‫الرئيسي‬ ‫المفتاح‬ ‫بإضافة‬ ‫يمكن‬‫ف‬(one)
‫الطرف‬ ‫في‬ ‫الموجود‬ ‫الكيان‬ ‫عن‬ ‫الناتجة‬ ‫العالقة‬ ‫إلى‬(many)ً‫خارجيا‬ ً‫مفتاحا‬ ‫ليصبح‬
‫فيها‬.
■‫لعدة‬ ‫عدة‬ ‫االرتباطات‬( :many-to-many)
–‫الك‬ ‫عن‬ ‫الناتجة‬ ‫للعالقات‬ ‫الرئيسية‬ ‫المفاتيح‬ ‫تتضمن‬ ‫عالقات‬ ‫بإضافة‬ ‫يمكن‬‫يانات‬
‫وي‬ ‫الجديدة‬ ‫للعالقة‬ ‫الرئيسي‬ ‫المفتاح‬ ‫مجتمعة‬ ‫تشكل‬ ‫والتي‬ ‫فيها‬ ‫المشاركة‬‫كل‬ ‫صبح‬
‫منه‬ ‫أتى‬ ‫الذي‬ ‫الكيان‬ ‫وعالقة‬ ‫الجديدة‬ ‫العالقة‬ ‫بين‬ ‫خارجي‬ ‫مفتاح‬ ‫منها‬.‫تضاف‬ ‫ثم‬
‫وجدت‬ ‫إن‬ ‫االرتباط‬ ‫واصفات‬.

Relational Model
( ‫النموذج‬‫العالقاتي‬ )
■‫عالقة‬/‫المدرس‬ ‫جدول‬
Attributes ‫واصفات‬
(or columns ‫)أعمدة‬
Tuples ‫صفوف‬
(or rows ‫)أسطر‬

Relational Model
( ‫النموذج‬‫العالقاتي‬ )
■‫المفاتيح‬:
–‫الرئيسي‬ ‫المفتاح‬(primary key)
■‫واصفات‬ ‫مجموعة‬ ‫أو‬ ‫واصفة‬ ‫هو‬‫أصغرية‬‫وحيد‬ ‫بشكل‬ ‫صف‬ ‫تحدد‬.
■‫مثل‬:ID‫للعالقة‬ ‫رئيسي‬ ‫مفتاح‬ ‫هو‬Instructor
–‫الخارجي‬ ‫المفتاح‬(Foreign key)
■‫الع‬ ‫في‬ ‫الواصفات‬ ‫إحدى‬ ‫لقيمة‬ ‫مقابلة‬ ‫قيمة‬ ‫وجود‬ ‫تضمن‬ ‫عالقتين‬ ‫لربط‬ ‫وسيلة‬ ‫هو‬‫القة‬
‫األولى‬(Referencing relation)‫الثانية‬ ‫العالقة‬ ‫ضمن‬(Referenced relation)
■‫مثل‬:dept_name‫العالقة‬ ‫في‬ ‫خارجي‬ ‫مفتاح‬ ‫هو‬Instructor‫في‬ ‫رئيسي‬ ‫مفتاح‬ ‫يقابله‬
‫العالقة‬department

STRUCTURED QUERY
LANGUAGE (SQL)
‫االستعالم‬ ‫لغة‬

Overview
■‫المعطيات‬ ‫قواعد‬ ‫لغات‬:
–‫المعطيات‬ ‫تعريف‬ ‫لغة‬( :DDL Data Definition Language)
–‫المعطيات‬ ‫مع‬ ‫التعامل‬ ‫لغة‬( :DML Data Manipulation Language)
■‫إجرائية‬ ‫لغات‬:‫إليها‬ ‫يحتاج‬ ‫التي‬ ‫المعطيات‬ ‫تحديد‬ ‫المستثمر‬ ‫من‬ ‫تتطلب‬‫ال‬ ‫وطريقة‬‫حصول‬
‫عليها‬.
■‫إجرائية‬ ‫غير‬ ‫لغات‬:‫إليها‬ ‫يحتاج‬ ‫التي‬ ‫المعطيات‬ ‫تحديد‬ ‫المستثمر‬ ‫من‬ ‫تتطلب‬‫ت‬ ‫دون‬‫حديد‬
‫عليها‬ ‫الحصول‬ ‫كيفية‬.

Overview

Data Definition Language (DDL)
(‫المعطيات‬ ‫تعريف‬ ‫)لغة‬
■ Create a Table (‫جدول‬ ‫)بناء‬
■ Examples:
– create table instructor (
ID char(5),
name varchar(20) not null,
dept_name varchar(20),
salary numeric(8,2),
primary key (ID),
foreign key (dept_name) references department)

Data Definition Language (DDL)
(‫المعطيات‬ ‫تعريف‬ ‫)لغة‬
■ Alter & Drop Tables: (‫وحذفها‬ ‫الجداول‬ ‫)تعديل‬
■ Examples:
– alter table r add A D
– alter table r drop A
– drop table r

Data Manipulation Language (DML)
(‫المعطيات‬ ‫مع‬ ‫التعامل‬ ‫)لغة‬
■ Insert (‫)اإلدخال‬
■ Examples:
– insert into course
values (’CS-437’, ’Database Systems’, ’Comp. Sci.’, 4);
– insert into course (course_id, title, credits, dept_name)
values (’CS-437’, ’Database Systems’, 4, ’Comp. Sci.’);
– insert into student
values (’3003’, ’Green’, ’Finance’, null);
– insert into student
select ID, name, dept_name, 0
from instructor;
– insert into table1 select * from table1;

■ Update (‫)التعديل‬
■ Examples:
– update instructor
set salary = salary * 1.03
where salary > 100000;

■ Delete (‫)الحذف‬
– delete from instructor
where dept name in (select dept name
from department
where building = ’Watson’);
where salary < (select avg (salary) from instructor);

Select Clause
Rule
■ Rule:
select A1, A2, ..., An
from r1, r2, ..., rm
where P
■ Examples:
– select *
from instructor
– select ID, name, salary/12
from instructor
– select distinct dept_name
from instructor

Select Clause
Conditions
■ select name
from instructor
where dept_name = ‘Comp. Sci.' and salary > 80000
■ select name, course_id
from instructor, teaches
where (instructor.ID, dept_name) = (teaches.ID, ’Biology’);

Select Clause
Join (‫)الضم‬
■ select *
■‫ديكارتي‬ ‫جداء‬ ‫يعني‬ ‫شروط‬ ‫بدون‬ ‫جدول‬ ‫من‬ ‫أكثر‬ ‫وجود‬.
■‫أخرى‬ ‫شروط‬ ‫بدون‬ ‫مفيد‬ ‫غير‬ ‫الديكارتي‬ ‫الجداء‬.

Select Clause
Join (‫)الضم‬
■‫شروط‬ ‫مع‬ ‫لكن‬ ‫ديكارتي‬ ‫جداء‬.
■‫مثال‬:
–‫أعطوها‬ ‫التي‬ ‫المواد‬ ‫أرقام‬ ‫مع‬ ً‫دروسا‬ ‫أعطوا‬ ‫الذين‬ ‫المدرسين‬ ‫أسماء‬ ‫أوجد‬
– select name, course_id
where instructor.ID = teaches.ID
–‫النظم‬ ‫قسم‬ ‫يعطيها‬ ‫التي‬ ‫للمواد‬ ‫والسنة‬ ‫والفصل‬ ‫وعنوانها‬ ‫المادة‬ ‫رقم‬ ‫أوجد‬
‫المعلوماتية‬
– select section.course_id, title, semester, year
from section, course
where section.course_id = course.course_id and dept_name = ‘Comp. Sci.'

Select Clause
Natural Join (‫الطبيعي‬ ‫)الضم‬
■ course natural join prereq

Select Clause
Outer Join (‫الخارجي‬ ‫)الضم‬
course natural left outer join prereq
course natural right outer join prereq
course natural full outer join prereq

Select Clause
Renaming (‫التسمية‬ ‫)إعادة‬
■‫كلمة‬ ‫باستخدام‬ ‫والواصفات‬ ‫العالقات‬ ‫تسمية‬ ‫إعادة‬ ‫يمكن‬as
■ select ID, name, salary/12 as monthly_salary
from instructor
■‫النظم‬ ‫قسم‬ ‫مدرسي‬ ‫أحد‬ ‫من‬ ‫أعلى‬ ً‫راتبا‬ ‫يقبضون‬ ‫الذين‬ ‫المدرسين‬ ‫أسماء‬ ‫أوجد‬
‫المعلوماتية‬
■ select distinct T.name
from instructor as T, instructor as S
where T.salary > S.salary and S.dept_name = ‘Comp. Sci.’

Select Clause
Order (‫النتائج‬ ‫)ترتيب‬
■‫واصفات‬ ‫عدة‬ ‫أو‬ ‫واصفة‬ ‫قيم‬ ‫بحسب‬ ‫ترتيب‬.
■‫الواصفة‬ ‫بحسب‬ ‫أبجدي‬ ‫أو‬ ‫رقمي‬ ‫ترتيب‬.
■‫تصاعدي‬ ‫ترتيب‬asc‫تنازلي‬ ‫أو‬desc
■ select distinct name
from instructor
order by name

Select Clause
(‫المحارف‬ ‫سالسل‬ ‫على‬ ‫)العمليات‬
■‫العملية‬ ‫باستخدام‬ ‫تقريبية‬ ‫مطابقة‬like
–‫معدومة‬ ‫تكون‬ ‫قد‬ ‫محارف‬ ‫مجموعة‬ ‫أو‬ ‫محرف‬ ‫لمطابقة‬ ‫خاص‬ ‫محرف‬%
–‫واحد‬ ‫محرف‬ ‫لمطابقة‬ ‫خاص‬ ‫محرف‬_
■ select name
from instructor
where name like '%dar%'
■‫المحرفين‬ ‫هذين‬ ‫أحد‬ ‫يتضمن‬ ‫عنه‬ ‫نبحث‬ ‫ما‬ ‫كان‬ ‫لو‬ ‫ماذا‬
–‫عن‬ ‫نبحث‬ ً‫مثال‬ ‫كنا‬ ‫إذا‬“100%”
–‫المحرف‬ ‫عمل‬ ‫نلغي‬%‫إلغاء‬ ‫محرف‬ ‫باستخدام‬like ‘100 %' escape ''
■‫المحارف‬ ‫سالسل‬ ‫على‬ ‫أخرى‬ ‫عمليات‬
–‫الدمج‬concatenation ( “||”)
–‫والكبيرة‬ ‫الصغيرة‬ ‫األحرف‬ ‫بين‬ ‫التحويل‬upper, lower
–‫محارف‬ ‫سلسلة‬ ‫طول‬length
–‫السلسلة‬ ‫من‬ ‫معين‬ ‫مكان‬ ‫من‬ ً‫بدءا‬ ‫معين‬ ‫بطول‬ ‫جزء‬ ‫استخراج‬substring

Select Clause
Set Operations (‫المجموعات‬ ‫على‬ ‫)العمليات‬
■ (select course_id from section where sem = ‘Fall’ and year = 2009)
union
(select course_id from section where sem = ‘Spring’ and year = 2010)
intersect
except
■‫مالحظة‬:
–‫آلي‬ ‫حذف‬‫للتكرارس‬
–‫العمليات‬ ‫تستخدم‬ ‫التكرار‬ ‫إلبقاء‬union all, intersect all, except all

Select Clause
Null Values (‫المعدومة‬ ‫)القيم‬
■‫واردة‬ ‫غير‬ ‫أو‬ ‫معروفة‬ ‫غير‬ ‫أو‬ ‫موجودة‬ ‫غير‬ ‫قيمة‬
■‫القيمة‬ ‫كانت‬ ‫إذا‬ ‫نختبر‬ ‫أن‬ ‫يمكن‬null‫الشرط‬ ‫باستخدام‬is null
■ select name
from instructor
where salary is null;
■‫القيمة‬ ‫تتضمن‬ ‫رياضية‬ ‫عملية‬ ‫نتيجة‬null‫هي‬null(5 + null = null)
■ OR: (unknown or true) = true
(unknown or false) = unknown
(unknown or unknown) = unknown
■ AND: (true and unknown) = unknown
(false and unknown) = false,
(unknown and unknown) = unknown
■ NOT: (not unknown) = unknown
■‫الطرفين‬ ‫أحد‬ ‫كان‬ ‫إذا‬ ‫المقارنة‬ ‫عمليات‬ ‫في‬null‫النتيجة‬ ‫تكون‬unknown
■‫التركيب‬ ‫نتيجة‬where‫أنها‬ ‫على‬ ‫معها‬ ‫التعامل‬ ‫يجري‬false‫تساوي‬ ‫كانت‬ ‫إذا‬unknown

Select Clause
Aggregate Functions (‫التجميع‬ ‫)توابع‬
■‫واحدة‬ ‫قيمة‬ ‫وتعيد‬ ‫قيم‬ ‫مجموعة‬ ‫دخلها‬ ‫في‬ ‫تأخذ‬ ‫توابع‬
■ select avg (salary)
from instructor
where dept_name= ’Comp. Sci.’;
■ select count (*)
from course;
■ select count (distinct ID)
from teaches
where semester = ’Spring’ and year = 2010;
■‫القيمة‬ ‫التجميع‬ ‫توابع‬ ‫تجاهل‬null
avg: average value
min: minimum value
max: maximum value
sum: sum of values
count: number of values

Select Clause
Group By (‫واصفة‬ ‫بحسب‬ ‫)التجميع‬
■‫مالحظات‬:
–‫واصفة‬ ‫من‬ ‫أكثر‬ ‫على‬ ‫التجميع‬ ‫يمكن‬
–‫قائمة‬ ‫في‬ ‫التجميعي‬ ‫التابع‬ ‫خارج‬ ‫الموجودة‬ ‫الواصفات‬ ‫جميع‬ ‫تظهر‬ ‫أن‬ ‫يجب‬group by
select dept_name, avg (salary)
from instructor
group by dept_name;

Select Clause
Having ‫التجميع‬ ‫على‬ ‫الشروط‬
■‫مالحظة‬:
–‫في‬ ‫الموجود‬ ‫الشرط‬ ‫يطبق‬having‫شرط‬ ‫يطبق‬ ‫بينما‬ ‫المجموعات‬ ‫تشكيل‬ ‫بعد‬where‫تشكيلها‬ ‫قبل‬
select dept_name, avg (salary)
from instructor
group by dept_name
having avg (salary) > 42000;

Views (‫)الرؤى‬
■‫الجداول‬ ‫على‬ ‫المعقدة‬ ‫االستعالمات‬ ‫لتسهيل‬ ‫وسيلة‬.
■ً‫فعليا‬ ‫مخزنة‬ ‫غير‬ ‫افتراضية‬ ‫جداول‬.
■‫بلغة‬ ‫مكتوبة‬ ‫اسم‬ ‫ولها‬ ‫مخزنة‬ ‫استعالمات‬SQL
■‫آخر‬ ‫جدول‬ ‫كأي‬ ‫استخدامها‬ ‫يمكن‬ ‫إنشائها‬ ‫بعد‬
■‫باستخدامها‬ ‫أخرى‬ ‫رؤية‬ ‫إنشاء‬ ‫حتى‬ ‫أو‬
■ create view v as < query expression >
– create view faculty as
select ID, name, dept_name
from instructor;
– select name
from faculty
where dept_name = ‘Biology’;
– create view bio_faculty as
select *
from faculty
where dept_name = ‘Biology’;

Transaction (‫المداولة‬ ‫)مفهوم‬
■ Commit (‫تثبيت‬ ‫)تعليمات‬
■ Rollback (‫إلغاء‬ ‫)تعليمات‬
■‫تعليمات‬DDLً‫تلقائيا‬ ‫بالتثبيت‬ ‫تقوم‬.

‫أخرى‬ ‫معطيات‬ ‫أنماط‬
■ Date:
– day, month, year ‘2005-7-27’
■ Time:
– hours, minutes, seconds ‘09:00:30’, ‘09:00:30.75’
■ Timestamp:
– date + time ‘2005-7-27 09:00:30.75’
■ interval period of time:
– timestamp1- timestamp2
■ Blob:
– binary large object (image, sound, movie, …)
■ Clob:
– character large object (memo, text book, …)

Question 1
■ The attributes made up of more than one single attributes are called:
A. Derived attribute
B. Composite attribute
C. Single value attribute
D. Multi value attribute

Question 2
■ Operations such as “and”. The result of:
true and unknown is _____
false and unknown is _____
unknown and unknown is _____
A. Unknown, unknown, false
B. True, false, unknown
C. True, unknow, unknown
D. Unknown, false, unknown

Question 3
■ Using the _____ clause retains only one copy of such identical tuples.
A. Null
B. Unique
C. Not null
D. Distinct

Question 4
■ In an employee table to include the attributes whose “value always have some
value” which of the following constraint must be used?
A. Null
B. Not null
C. Unique
D. Distinct

Question 5
■ Aggregate functions are functions that take a _____ as input and return a single
value.
A. Collection of values
B. Single value
C. Aggregate value
D. Both collection of values & single value

Question 6
■ All aggregate functions except _____ ignore null values in their input collection.
A. Count(attribute)
B. Count(*)
C. Avg
D. Sum

Question 7
■ Aggregate functions can be used in the select list or the _____ clause of a select
statement or subquery. They cannot be used in a _____ clause.
A. Where, having
B. Having, where
C. Group by, having
D. Group by, where

Question 8
■ Which of the following deletes all the entries but keeps the structure of the relation.
A. Delete from r where P;
B. Delete from instructor where dept name = ‘Finance’;
C. Delete from instructor where salary between 13000 and 15000;
D. Delete from instructor;

Question 9
■ Fill in with correct keyword to update the instructor relation
Update instructor _____ salary = salary * 1.05;
A. Where
B. Set
C. In
D. select

Question 10
■ Which of the join operations do not preserve non matched tuples?
A. Left outer join
B. Right outer join
C. Inner join
D. Natural join

Question 11
■ How many tables may be included with a join?
A. One
B. Two
C. Three
D. All of the mentioned

Question 12
■ Data integrity constraints are used to:
A. Control who is allowed access to the data
B. Ensure that duplicate records are not entered into the table
C. Improve the quality of data entered for a specific property
D. Prevent users from changing the values stored in the table

Question 13
■ In order to ensure that an instructor’s salary domain allows only values greater than
a specified value use:
A. Value >= 30000.00
B. Not null;
C. Check(value >= 29000.00);
D. Check(value)

Question 14
■ Which of the following statement is used to remove the privilege from the user Amir?
A. Remove update on department from Amir
B. Revoke update on employee from Amir
C. Delete select on department from Raj
D. Grant update on employee from Amir

Question 15
■ Which of the following is another name for a weak entity?
A. Child
B. Owner
C. Dominant

Question 16
■ E-R model uses which symbol to represent weak entity set:
A. Dotted rectangle
B. Diamond
C. Doubly outlined rectangle
D. None of the above

XML
■ Structure
– Elements and Attributes
– Namespaces
– DTD
– XML Schema
■ Query
– XPath
– XQuery (FLOWER)
– XSLT

XML Introduction
■ XML (eXtensible Markup Language)
■ semi-structured data models.
■ Derived from SGML (Standard Generalized Markup Language)
■ Documents have tags giving extra information about sections of the document
– <title> XML </title> <slide> Introduction …</slide>
■ Extensible, unlike HTML Users can add new tags.
■ The ability to specify new tags, and to create nested tag structures make XML a
great way to exchange data, not just documents.
■ Elements must be properly nested

XML Namespaces
■ Usage:
– XML data has to be exchanged between organizations.
– Same tag name may have different meaning in different organizations, causing confusion on
exchanged documents.
■ Example:
<university xmlns:yale=“http://www.yale.edu”>
…
<yale:course>
<yale:course_id> CS-101 </yale:course_id>
<yale:title> Intro. to Computer Science</yale:title>
<yale:dept_name> Comp. Sci. </yale:dept_name>
<yale:credits> 4 </yale:credits>
</yale:course>
…
</university>

XML (DTD)
Document Type Definition
■ The type of an XML document can be specified using a DTD
■ DTD constraints structure of XML data
– What elements can occur
– What attributes can/must an element have
– What subelements can/must occur inside each element, and how many times.
■ DTD does not constrain data types
– All values represented as strings in XML
■ DTD syntax
– <!ELEMENT element (subelements-specification) >
– <!ATTLIST element (attributes) >

XML Schema
■ XML Schema is a more sophisticated schema language which addresses the
drawbacks of DTDs.
■ Supports:
– Typing of values
■ integer, string, etc
■ constraints on min/max values
– User-defined, complex types
– Many more features, including
■ uniqueness and foreign key constraints, inheritance

XML XPath
■ XPath is used to address (select) parts of documents using path expressions
■ A path expression is a sequence of steps separated by “/”
■ Examples:
– /university-3/instructor/name
■ <name>Srinivasan</name>
■ <name>Brandt</name>
– /university-3/instructor/name/text( )
■ returns the same names, but without the enclosing tags
– /university-3/course[credits >= 4]
■ returns course elements with a credit value greater or equal 4
– /university-3/course[credits >= 4]/@course_id
■ returns the course identifiers of courses with credits >= 4

XML XQuery
■ XQuery is a general purpose query language for XML data
■ XQuery uses a
for … let … where … order by … return…
■ Syntax
– For <--> SQL from
– Where <--> SQL where
– order by <--> SQL order by
– return <--> SQL select
– let allows temporary variables, and has no equivalent in SQL

XML XQuery
FLWOR Syntax
■ Examples:
– find all courses with credits > 3, with each result enclosed in an <course_id> ..
</course_id> tag
for $x in /university-3/course
let $courseId := $x/@course_id
where $x/credits > 3
return <course_id> { $courseId } </course id>
■ Items in the return clause are XML text unless enclosed in {}, in which case they are
evaluated

Question 1
■ What does XML stand for?
A. eXtra Modern Link
B. eXtensible Markup Language
C. Example Markup Language
D. X-Markup Language

Question 2
■ What is the correct syntax of the declaration which defines the XML version?
A. <xml version=“1.0”/>
B. <?xml version=“1.0”?>
C. <?xml version=“1.0”/>

Question 3
■ Is it easier to process XML than HTML?
A. Yes
B. No
C. Sometimes
D. Cant say

Question 4
■ Kind of Parsers are
A. Well-formed
B. Well-documented
C. Non-validating and validating

Question 5
■ Well formed XML document means
A. It contains a root element
B. It contain an element
C. It contains one or more elements
D. Must contain one or more elements and root element must contain all other
elements

Question 6
■ Comment in XML document is given by
A. <?-- -->
B. 
D. </-- -->

Question 7
■ XML uses the features of
A. HTML
B. XHTML
C. VML
D. SGML

Question 8
■ What does DTD stand for?
A. Direct Type Definition
B. Document Type Definition
C. Dynamic Type Definition

Question 9
■ Which of the following XML fragments are well-formed?
A. <myElement myAttribute=“someValue”/>
B. <myElement myAttribute=someValue/>
C. <myElement myAttribute=‘someValue’/>
D. <myElement myAttribute=“someValue’/>

Question 10
■ How can we make attributes have multiple values:
A. <myElement myAttribute=“value1 value2”/>
B. <myElement myAttribute=“value1” myAttribute=“value2”/>
C. <myElement myAttribute=“value1,value2”/>
D. Attributes cannot have multiple values

Question 11
■ In XML
A. The internal DTD subset is read before the external DTD
B. The external DTD subset is read before the internal DTD
C. There is no external type of DTD
D. There is no internal type of DTD

Question 12
■ Is this a “well formed” XML document?
<?xml version=“1.0”?>
<note>
<to age=29>Tove</to>
<from>Jani</from>
</note>
A. True
B. False

Question 13
■ XML preserves white spaces
A. True
B. False

NORMALIZATION

Normalization Process
1NF
2NF
3NF
3.5NF
4NF

Normalization Process
■ Every table in your Database should at least follow the 1st Normal Form, always.
■ Or stop using Database!!

1st Normal Form
■ There are 4 basic rules that a table should follow to be in 1st Normal Form.

1st Normal Form
Rule 1
■ Each column should contain atomic
values.
■ Entries like X,Y and W,X violate this
rule.

1st Normal Form
Rule 2
■ A column should contain values that
are of the same type.
■ Do not inter-mix different types of
values in any column.

1st Normal Form
Rule 3
■ Each column should have a unique
name.
■ Same names leads to confusion at the
time of data retrieval.

1st Normal Form
Rule 4
■ Order in which data is saved doesn’t
matter.
■ Using SQL query. You can easily fetch
data in any order from a table.

1st Normal Form
Example

2nd Normal Form
■ For a table to be in the Second Normal Form:
– It should be in 1st Normal Form.
– And, it should not have any Partial Dependencies.

2nd Normal Form
What is Partial Dependency?
■ To understand Partial Dependency.
■ We first need to understand what Dependency is?

2nd Normal Form

2nd Normal Form
■ Primary Key should be score_id
■ But student_id + subject_id together makes a more meaningful primary key.

2nd Normal Form
This is Partial Dependency
Teacher column only
depends on subject
and not on student.

2nd Normal Form
Move teacher column to Subject table

2nd Normal Form

3rd Normal Form

3rd Normal Form
■ For a table to be in 3rd Normal Form:
– It should be in 2nd Normal Form.
– And it should not have Transitive Dependency.

3.5 Normal Form (BCNF)
Boyce-Codd Normal Form
■ Tables should satisfy 2 conditions:
– It should be in the 3rd Normal Form.
– For any dependency A → B, A should be a super key.

3.5 Normal Form (BCNF)
Boyce-Codd Normal Form

4th Normal Form
■ It should satisfy BCNF.
■ It should not have Multi-Valued Dependency.

4th Normal Form

4th Normal Form
2 independent tables

Question 1
■ In the _____ normal form, a composite attribute is converted to individual attributes.
A. First
B. Second
C. Third
D. Fourth

Question 2
■ Tables in second normal form (2NF)
A. Eliminate all hidden dependencies
B. Eliminate the possibility of a insertion anomalies
C. Have a composite key
D. Have all non key fields depend on the whole primary key

Question 3
■ Which forms are based on the concept of functional dependency
A. 1NF
B. 2NF
C. 3NF
D. 4NF

RATIONAL ALGEBRA

Question 1
■ If E1 and E2 are relational algebra expressions, then which of the following is NOT a
relational algebra expression?
A. E1 ∪ E2
B. E1 / E2
C. E1 – E2
D. E1 x E2

Question 2
■ Which clause from the following corresponds to the projection operation of the
relational algebra?
A. From
B. Select
C. Where
D. Group by

Question 1
■ A relational database consists of a collection of
A. Tables
B. Fields
C. Records
D. Keys

Question 2
■ The term _______ is used to refer to a row.
A. Attribute
B. Tuple
C. Field
D. Instance

Question 3
■ The term attribute refers to a ___________ of a table.
A. Record
B. Column
C. Tuple
D. Key

Question 4
■ Database __________ which is the logical design of the database, and the database
_______ which is a snapshot of the data in the database at a given instant in time.
A. Instance, Schema
B. Relation, Schema
C. Relation, Domain
D. Schema, Instance

Question 5
■ Course (course_id,sec_id,semester)
Here the course_id,sec_id and semester are __________ and course is a _________
A. Relations, Attribute
B. Attributes, Relation
C. Tuple, Relation
D. Tuple, Attributes

Question 6
■ The tuples of the relations can be of ________ order
A. Any
B. Same
C. Sorted
D. Constant

Question 7
■ Which one of the following attribute can be taken as a primary key ?
A. Name
B. Street
C. Id
D. Department

Question 8
■ The ______ is the one in which the primary key of one relation is used as a normal
attribute in another relation.
A. Referential relation
B. Referencing relation
C. Referenced relation
D. Referred relation

Question 9
■ The _____ operation allows the combining of two relations by merging pairs of
tuples, one from each relation, into a single tuple
A. Select
B. Join
C. Union
D. Intersection

Question 10
■ The result which operation contains all pairs of tuples from the two relations,
regardless of whether their attribute values match
A. Join
B. Cartesian product
C. Intersection
D. Set difference

Question 11
■ The _______ operation performs a set union of two “similarly structured” tables
A. Union
B. Join
C. Product
D. Intersect

Question 12
■ The _______ operator takes the results of two queries and returns only rows that
appear in both result sets
A. Union
B. Intersect
C. Difference
D. Projection

Question 13
■ Which one of the following is used to define the structure of the relation ,deleting
relations and relating schemas ?
A. DML (Data Manipulation Language)
B. DDL (Data Definition Language)
C. Query
D. Relational Schema

Question 14
■ Which one of the following provides the ability to query information from the
database and to insert tuples into, delete tuples from, and modify tuples in the
database ?
A. DML (Data Manipulation Language)
B. DDL (Data Definition Language)
C. Query
D. Relational Schema

Question 15
■ The basic data type char(n) is a _____ length character string and varchar(n) is
_____ length character.
A. Fixed, equal
B. Equal, variable
C. Fixed, variable
D. Variable, equal

Question 16
■ Insert into instructor values (10211, ’Smith’, ’Biology’, 66000);
What type of statement is this ?
A. Query
B. DML
C. Relational
D. DDL

Question 17
■ Select ________ dept_name
from instructor;
Here which of the following displays the unique values of the column ?
A. All
B. From
C. Distinct
D. Name

Question 18
■ The ______ clause allows us to select only those rows in the result relation of the
____ clause that satisfy a specified predicate
A. Where, from
B. From, select
C. Select, from
D. From, where

Question 19
■ Which of the following statements contains an error?
A. Select * from emp where emp id = 10003;
B. Select empid from emp where lastname = GELLER;
C. Select emp id from emp;
D. Select empid where empid = 1009 and lastname = ‘GELLER’;

Question 20
■ Which keyword must be used here to rename the field name ?
A. From
B. Rename
C. As
D. Join

Question 21
■ SELECT * FROM employee WHERE dept_name="Comp Sci";
■ In the SQL given above there is an error . Identify the error
A. Dept_name
B. Employee
C. “Comp Sci”
D. From

Question 22
■ SELECT emp_name FROM department
■ WHERE dept_name LIKE ’ __ Computer Science’;
■ Which one of the following has to be added into the blank to select the dept_name
which has Computer Science as its ending string ?
A. %
B. _
C. ||
D. $

Question 23
■ ’_ _ _ ’ matches any string of ______ three characters.
■ ’_ _ _ %’ matches any string of ______ three characters.
A. At least, Exactly
B. Exactly, At least
C. At least, All
D. All, Exactly

Question 24
■ By default, the order by clause lists items in ______ order.
A. Descending
B. Any
C. Same
D. Ascending

Question 25
■ To display the salary from greater to smaller and name in ascending order which of
the following options should be used?
A. Ascending, Descending
B. Asc, Desc
C. Desc, Asc
D. Descending, Ascending

Question 26
■ SELECT instructor.*
■ FROM instructor, teaches
■ WHERE instructor.ID= teaches.ID;
■ This query does which of the following operation?
A. All attributes of instructor and teaches are selected
B. All attributes of instructor are selected on the given condition
C. All attributes of teaches are selected on given condition
D. Only the some attributes from instructed and teaches are selected

Question 27
■ In SQL the spaces at the end of the string are removed by _______ function
A. Upper
B. String
C. Trim
D. Lower

Question 28
■ _____ operator is used for appending two strings
A. &
B. %
C. ||
D. _

Question 29
■ The union operation automatically __________ unlike the select clause
A. Adds tuples
B. Eliminates unique tuples
C. Adds common tuples
D. Eliminates duplicate

Question 29
■ The union operation automatically __________ unlike the select clause.
A. Adds tuples
B. Eliminates unique tuples
C. Adds common tuples
D. Eliminates duplicate

Question 30
■ The predicate in a where clause can involve Boolean operations such as and
■ The result of: true and unknown is _____
false and unknown is _____
unknown and unknown is _____
A. Unknown, unknown, false
B. True, false, unknown
C. True, unknown, unknown
D. Unknown, false, unknown

Question 31
■ Using the ______ clause retains only one copy of such identical tuples
A. Null
B. Unique
C. Not null
D. Distinct

Question 32
■ In an employee table to include the attributes whose value always have some value
which of the following constraint must be used?
A. Null
B. Not null
C. Unique
D. Distinct

Question 33
■ Aggregate functions are functions that take a ___________ as input and return a
single value
A. Collection of values
B. Single value
C. Aggregate value
D. Both Collection of values & Single value

Question 34
■ All aggregate functions except _____ ignore null values in their input collection.
A. Count(attribute)
B. Count(*)
C. Avg
D. Sum

Question 35
■ Aggregate functions can be used in the select list or the _______ clause of a select
statement or subquery. They cannot be used in a ______ clause.
A. Where, having
B. Having, where
C. Group by, having
D. Group by, where

Question 36
■ Which one of the following deletes all the entries but keeps the structure of the
relation.
A. Delete from r where P;
B. Delete from instructor where dept name= ’Finance’;
C. Delete from instructor where salary between 13000 and 15000;
D. Delete from instructor;

Question 37
■ UPDATE instructor _____ salary= salary * 1.05;
■ Fill in with correct keyword to update the instructor relation.
A. Where
B. Set
C. In
D. Select

Question 38
■ Which of the join operations do not preserve non matched tuples?
A. Left outer join
B. Right outer join
C. Inner join
D. Natural join

Question 39
■ How many tables may be included with a join?
A. One
B. Two
C. Three

Question 40
■ Data integrity constraints are used to:
A. Control who is allowed access to the data
B. Ensure that duplicate records are not entered into the table
C. Improve the quality of data entered for a specific property
D. Prevent users from changing the values stored in the table

Question 41
■ In order to ensure that an instructor’s salary domain allows only values greater than
a specified value use:
A. Value>=30000.00
B. Not null;
C. Check(value >= 29000.00);
D. Check(value)

Question 42
■ Which of the following statement is used to remove the privilege from the user Amir?
A. Remove update on department from Amir
B. Revoke update on employee from Amir
C. Delete select on department from Raj
D. Grant update on employee from Amir

Question 43
■ Which of the following is another name for a weak entity?
A. Child
B. Owner
C. Dominant

Question 44
■ In the __________ normal form, a composite attribute is converted to individual
attributes.
A. First
B. Second
C. Third
D. Fourth

Question 45
■ The syntax of a user query is verified by:
A. Query optimizer
B. DBA
C. Parser

Question 46
■ DBA stands for:
A. Data Bank Access.
B. Database Access.
C. Data Bank Administration.
D. Database Administrator.

Question 47
■ E-R model uses which symbol to represent weak entity set :
A. Dotted rectangle
B. Diamond
C. Doubly outlined rectangle.
D. None of the above.

Question 48
■ The attributes made up of more than one single attributes are called :
A. Derived attribute
B. Composite attribute
C. Single value attribute
D. Multi value attribute

Question 49
■ What is the correct syntax of the declaration which defines the XML version?
A. <xml version="A.0" />
B. <?xml version="A.0"?>
C. <?xml version="A.0" />

Question 50
■ Which of the following strings are a correct XML name?
A. xmlExtension
B. xslNewElement
C. XMLElement#123
D. All

Question 51
■ Which clause from the following corresponds to the projection operation of the
relational algebra ?
A. From
B. Select
C. Where
D. Group by

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