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Questions and Answers
What is the primary goal of converting a database table from 2NF to 3NF?
What is the primary goal of converting a database table from 2NF to 3NF?
Which functional dependency is represented in the Enrollments Relation after conversion to 3NF?
Which functional dependency is represented in the Enrollments Relation after conversion to 3NF?
Which of the following is NOT a benefit of converting a database to 3NF?
Which of the following is NOT a benefit of converting a database to 3NF?
In the context of lossless join decomposition, which characteristics are preferred?
In the context of lossless join decomposition, which characteristics are preferred?
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Which of the following SQL JOIN types returns all records from the left table and the matched records from the right table?
Which of the following SQL JOIN types returns all records from the left table and the matched records from the right table?
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Which type of SQL JOIN retrieves matching rows from both tables based on a related column?
Which type of SQL JOIN retrieves matching rows from both tables based on a related column?
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What is the key distinction between a Natural Join and an Inner Join?
What is the key distinction between a Natural Join and an Inner Join?
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In the given relations, what would the result of a FULL OUTER JOIN between the Enrollments and Courses tables yield?
In the given relations, what would the result of a FULL OUTER JOIN between the Enrollments and Courses tables yield?
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What is the primary reason for decomposing a table to achieve 2NF?
What is the primary reason for decomposing a table to achieve 2NF?
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Which functional dependency indicates a transitive dependency?
Which functional dependency indicates a transitive dependency?
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Which statement is true about a relation in 3NF?
Which statement is true about a relation in 3NF?
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When performing a natural join between two tables, what condition must be met?
When performing a natural join between two tables, what condition must be met?
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Which type of join is used to return all records from the left table and matched records from the right table?
Which type of join is used to return all records from the left table and matched records from the right table?
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What characteristic distinguishes outer joins from inner joins?
What characteristic distinguishes outer joins from inner joins?
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What does lossless join decomposition ensure?
What does lossless join decomposition ensure?
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In the given functional dependency 'StudentID, CourseID → CourseName', which attributes are candidate keys?
In the given functional dependency 'StudentID, CourseID → CourseName', which attributes are candidate keys?
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What is the primary function of the EQUI JOIN in SQL?
What is the primary function of the EQUI JOIN in SQL?
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Which type of SQL JOIN retains all records from the left table and only matched records from the right?
Which type of SQL JOIN retains all records from the left table and only matched records from the right?
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What distinguishes a Natural Join from an Inner Join in SQL?
What distinguishes a Natural Join from an Inner Join in SQL?
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How many types of Outer Joins are mentioned?
How many types of Outer Joins are mentioned?
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What is a key characteristic of conflict serializability in a schedule?
What is a key characteristic of conflict serializability in a schedule?
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Which statement best describes the purpose of a functional dependency in database design?
Which statement best describes the purpose of a functional dependency in database design?
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What results from a schedule that is not conflict serializable?
What results from a schedule that is not conflict serializable?
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What is the result of performing a Full Outer Join between two tables?
What is the result of performing a Full Outer Join between two tables?
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Study Notes
Normalization in DBMS
- Normalization is the process of arranging data in a database to reduce redundancy and improve data integrity.
- It involves dividing a large table into smaller ones and defining relationships between them.
- Normalization helps eliminate unwanted features like insertion, update, and deletion anomalies.
Need of Normalization
- Eliminating anomalies is the primary goal of normalization.
- Redundancy, data integrity issues, and difficulties scaling a database are also addressed.
- Normalization provides a structured approach to database design.
Data Modification Anomalies
- Insertion Anomaly: Cannot insert a new tuple in a relationship due to missing data.
- Deletion Anomaly: Deleting data unintentionally removes other important data.
- Update Anomaly: Updating a single data value requires changes on multiple rows.
Types of Normal Forms
- Normalization works through a series of stages called normal forms.
- Normal forms apply to individual relations.
- A relation is said to be in a particular normal form if it satisfies specific constraints.
First Normal Form (1NF)
- A table is in 1NF if each column contains only atomic (indivisible) values.
- Repeating groups or arrays in columns are not allowed.
- All entries in a column must be of the same data type.
Second Normal Form (2NF)
- A table is in 2NF if it's in 1NF, and every non-key attribute is fully functionally dependent on the entire primary key.
- There are no partial dependencies on the primary key.
Third Normal Form (3NF)
- A table is in 3NF if it's in 2NF, and there are no transitive dependencies.
- A non-key attribute must not depend on another non-key attribute.
Boyce-Codd Normal Form (BCNF)
- A stronger definition of 3NF.
- A relation is in BCNF if for every non-trivial functional dependency X→Y, X is a superkey.
Fourth Normal Form (4NF)
- A relation is in 4NF if it's in BCNF and there are no multi-valued dependencies besides a candidate key.
- No multi-valued dependencies are allowed except on candidate keys.
Transaction in DBMS
- A transaction is a logical unit of work consisting of operations which are all logically related.
- Main operations: read and write.
ACID Properties of Transaction
- Atomicity: The transaction is completed completely or not at all.
- Consistency: The database's integrity constraints are maintained.
- Isolation: Multiple transactions can occur simultaneously without problems.
- Durability: Changes made by a successful transaction are saved permanently to disk.
Concurrency Problems in DBMS
- In a DBMS, when multiple transactions execute concurrently, there may be issues.
- These issues arise from a lack of control regarding how transactions are handled simultaneously.
- Possible Problems: Dirty Read, Unrepeatable read,Lost Update, Phantom Read.
Types of Concurrency Control Problem
- Dirty read.
- Unrepeatable read.
- Lost update problem.
- Phantom read problem.
Serializability in DBMS
- The order in which multiple transactions execute in a DBMS.
- Serial schedule: Operations of transactions occur one after another.
- Non-serial schedule: Operations of transactions can be interleaved.
- Conflict Serializable: a non-serial schedule that can be converted into a serial schedule by swapping non-conflicting operations
- View Serializable: if a schedule is conflict serializable, it is view serializable
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Description
This quiz covers the concept of normalization in databases, focusing on its importance and the various types of anomalies it addresses. It delves into the structured approach normalization provides, eliminating redundancy and improving data integrity. Test your knowledge on the significance and methodology of normalization in Database Management Systems.
