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ISDS 3110 Final Exam Guide correctly answered already passed
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ISDS 3110 Final Exam Guide correctly answered already passed
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ISDS 3110 Final Exam GuidePattern Match Search Condition - *LIKE / NOT LIKE* - correct answer ✔✔*%*
- Represents any sequence of zero or more characters (wildcard)
*_*(underscore)
- Represents any single character
Subqueries - correct answer ✔✔A query within a query
*Multi-Table Join with Selection Predicates* example.
List the fname and lname of clients who are registered in branches in 'London'. - correct answer
✔✔*SELECT DISTINCT* c.fName, c.lName *FROM* Client c, Registration r, Branch b *WHERE* c.clientNo
= r.clientNo *AND* r.branchNo = b.branchNo *AND* b.city = 'London'
Motivation for Normalization - correct answer ✔✔Problem 1. Data Redundancy
Problem 2. Update Anomalies
Update Anomaly - correct answer ✔✔Relations that contain redundant information may potentially
suffer from update anomalies
Types of Update Anomalies - correct answer ✔✔- *Insertion* anomaly
- *Deletion* Anomaly
- *Modification* Anomaly
, Solution to Avoid Update Anomalies - correct answer ✔✔Decomposition
Decomposition must satisfy 2 properties: - correct answer ✔✔1. *lossless-join* property
- enables us to find any instance of the original relation from corresponding instances in the smaller
relations
2. *Dependency Preservation* Property
- Enables us to enforce a constraint on the original relation by enforcing some constraint on each of the
smaller relations
Purpose of Normalization - correct answer ✔✔*Normalization* is a *database design technique* for
*producing* a *set of suitable relations* that support the data requirements of an enterprise
Characteristics of a suitable set of relations - correct answer ✔✔a. *The minimal number of attributes*
necessary to support the data requirements of the enterprise
b. attributes with a close logical relationship are found in the same relation
c. *Minimal data redundancy* with each attribute represented only once with the important exception
of attributes that form all or part of foreign keys
Benefits of Normalization - correct answer ✔✔a. Easier for the end user to access and maintain the data
b. Take up minimal storage space on the computer
Functional Dependencies - correct answer ✔✔If *A* and *B* are attributes of relation R
*B* is *functionally dependent* on *A* (denoted A -> B) If each value of *A* in R is *associated* with
*exactly one *value of *B* in R
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