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SQL and Relational Databases 101 Cognitive Class Exam Quiz Answers

SQL and Relational Databases 101 Cognitive Class Certification Answers

Question 1: What is a Database?

  • A program that stores data
  • Stores data in tabular form
  • A repository of data
  • All of the above

Question 2: Advantages of the relational model include:

  • Provides logical and physical data independence
  • Data is stored in simple data structures
  • It is the most used data model
  • All of the above

Question 3: In an Entity-Relationship diagram, the Entity Name maps to the Table name, the attributes map to the …

  • Table rows and columns
  • Table columns
  • Table rows
  • None of the above

Question 1: Which of the following statements is true?

  • A table can have a primary key and a foreign key
  • A Foreign Key is a set of columns referring to a primary key of another table
  • A primary key uniquely identifies each row in a table
  • All of the above

Question 2: Which Relational Constraint prevents duplicate values in a table?

  • Entity Integrity constraint
  • Null constraint
  • Check constraint
  • All of the above

Question 3: The Semantic Integrity Constraint defines the relationships between tables. (T/F)

  • True
  • False

Question 1: The Primary Key of a relational table uniquely identifies each _____ in a table.

  • column
  • row
  • Both of the above
  • Neither of the above

Question 2: The INSERT statement cannot be used to insert multiple rows in a single statement. (T/F)

  • True
  • False

Question 3: The SELECT statement is called a Query, and the output we get from executing the query is called a Result Set.  (T/F)

  • True
  • False

Question 1: You want to select an author’s name from a table, but you only remember the author’s last name starts with the letter B, which string pattern can you use?

  • SELECT lastname from author where lastname like ‘B$’
  • SELECT lastname from author where lastname like ‘B%’
  • SELECT lastname from author where lastname like ‘B#’
  • None of the above

Question 2: In a SELECT statement, which SQL clause controls how the result set is displayed?

  • ORDER BY clause
  • ORDER IN clause
  • ORDER WITH clause

Question 3: Which SELECT statement eliminates duplicates in the result set?

  • SELECT country from author ORDER BY 1
  • SELECT distinct(country) from author
  • SELECT unique(country) from author
  • None of the above

Question 1: An INNER JOIN returns only the rows that match. (T/F)

  • True
  • False

Question 2: A LEFT OUTER JOIN displays all the rows from the right table, and combines matching rows from the left table. (T/F)

  • True
  • False

Question 3: When using an OUTER JOIN, you must explicitly state that you want either a LEFT JOIN or a RIGHT JOIN. (T/F)

  • True
  • False

Question 1: The 5 basic SQL commands are…

  • CREATE, SELECT, INSERT, UPDATE, DELETE
  • CREATE, ALTER, INSERT, UPDATE, DELETE
  • CREATE, SELECT, INSERT, MODIFY, DELETE
  • All of the above

Question 2: The blueprint of any database system is the …

  • Data model
  • Information model
  • Both of the above

Question 3: Attributes help clarify relationship diagrams (T/F)

  • True
  • False

Question 4: A table containing one or more foreign keys is called a Parent table. (T/F)

  • True
  • False

Question 5: The Referential Integrity Constraint ensures the validity of the data using a combination of Primary Keys and Foreign Keys.

  • True
  • False

Question 6: What are the basic categories of the SQL language based on functionality?

  • Data Manipulation Language
  • Data Definition Language
  • Both of the above
  • Neither of the above

Question 7: The CREATE TABLE statement is a….

  • DDL statement
  • DML statement
  • Both of the above

Question 8: When using the UPDATE statement, if you do not specify the WHERE clause, all the rows in the table are updated.

  • True
  • False

Question 9: You want to select a list of books whose number of pages is between 100 and 200 . Select the correct query from the following options.

  • SELECT title, pages from book where pages BETWEEN 100 AND 200
  • SELECT title, pages from book where pages RANGE 100 AND 200
  • SELECT title, pages from book where pages less than or equal to 100 AND pages greater than or equal to 200
  • A or B
  • All the options above are correct

Question 10: What is the default sorting mode of the ORDER BY clause?

  • Ascending
  • Descending
  • Randomly selected order
  • None of the above
  • All of the above

Question 11: Which of the following can be used in a SELECT statement to restrict a result set?

  • HAVING
  • GROUP BY
  • DISTINCT
  • All of the above

Question 12: The HAVING clause works only with the GROUP BY clause. (T/F)

  • True
  • False

Question 13: Which of the following are valid types of OUTER JOIN?

  • LEFT OUTER JOIN
  • RIGHT OUTER JOIN
  • FULL OUTER JOIN
  • A and B only
  • All of the above

Question 14: A FULL JOIN returns only the rows that match. (T/F)

  • True
  • False

Question 15: To combine tables in relational databases, we use:

  • Table names
  • Matching values/Primary key
  • Tables cannot be combined
  • None of the above options are correct

Question 16: >> True or False: Semantic integrity ensures that data entered into a row reflects an allowable value for that row.

  • True
  • False

Question 17: Which of the following statements are correct about databases:

  • A database represents some aspect of the real world
  • A database is a logically coherent collection of data with some inherent meaning
  • A database is designed, built and populated with data for a specific purpose
  • All the above options are correct

Question 18: Which of the following statements are correct about primary keys

  • The value of the Primary Key must be unique for each instance of the entity.
  • There can be no missing values (i.e., Not Null) for Primary Keys.
  • The Primary Key is immutable .i.e., once created the value of the Primary Key cannot be changed.
  • All the above options are correct

Question 19: The ____________ keyword is used to eliminate duplicate tuples from the result set of an SQL query.

  • COMMON
  • DISTINCT
  • ALL
  • EXISTS

Question 20: Select the correct statements about the join operator

  • Primary Key- Foreign Key is the common join operator
  • Is used to combine more than one table
  • You have to know the relationship between the tables
  • None of the Statements are correct

Introduction to SQL and Relational Databases 101

SQL (Structured Query Language) is a powerful tool used for managing and manipulating data in relational databases. Here’s a basic overview:

  1. What is a Relational Database?
    • A relational database is a type of database that stores and organizes data into tables (or relations) with predefined relationships between them. These relationships are defined by keys (usually primary and foreign keys).
  2. SQL Basics:
    • SQL is a language used to interact with relational databases. It allows you to perform various operations such as querying data, inserting new data, updating existing data, and deleting data.
  3. Common SQL Commands:
    • SELECT: Retrieves data from one or more tables.
    • INSERT: Adds new rows of data into a table.
    • UPDATE: Modifies existing data in a table.
    • DELETE: Removes rows of data from a table.
    • CREATE TABLE: Creates a new table in the database.
    • ALTER TABLE: Modifies an existing table structure.
    • DROP TABLE: Deletes a table from the database.
    • JOIN: Combines rows from two or more tables based on a related column between them.
    • GROUP BY: Groups rows that have the same values into summary rows.
    • ORDER BY: Sorts the result set in ascending or descending order.
    • WHERE: Filters records based on specified conditions.
  4. Data Types:
    • SQL supports various data types such as integer, float, varchar, date, etc. These data types define the kind of data that can be stored in a column of a table.
  5. Constraints:
    • Constraints are rules enforced on data columns to ensure the accuracy and reliability of the data. Common constraints include:
      • Primary Key: Uniquely identifies each record in a table.
      • Foreign Key: Establishes a link between two tables.
      • NOT NULL: Ensures a column cannot have NULL values.
      • UNIQUE: Ensures all values in a column are different.
      • CHECK: Ensures that all values in a column satisfy certain conditions.
      • DEFAULT: Sets a default value for a column when no value is specified.
  6. Normalization:
    • Normalization is the process of organizing data in a database to reduce redundancy and improve data integrity. It involves dividing large tables into smaller tables and defining relationships between them.
  7. Indexing:
    • Indexes are used to speed up data retrieval operations by providing quick access to rows in a table. They are created on one or more columns of a table and allow the database management system to locate data quickly without having to scan the entire table.
  8. Transactions:
    • A transaction is a sequence of SQL statements that are executed as a single unit of work. It follows the ACID properties (Atomicity, Consistency, Isolation, Durability) to ensure data integrity and reliability.
  9. Security:
    • SQL databases provide various security features such as user authentication, authorization, and encryption to protect data from unauthorized access and ensure data privacy.
  10. Backup and Recovery:
    • Regular backups of databases are essential to prevent data loss in case of hardware failure, human error, or other disasters. Database management systems offer tools and mechanisms for backup and recovery operations.

Understanding these fundamental concepts will give you a good foundation for working with SQL and relational databases.

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