CompTIA DS0-001 Online Practice Questions and Exam Preparation

CompTIA DS0-001 Online Questions & Answers

• Question 91:

  Which of the following is an advantage of creating indexes?

  A. To help with space allocation
  B. To provide quick and efficient access to data
  C. To reduce memory
  D. To update the query plan
  B. To provide quick and efficient access to data

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  Explanation/Reference:

  The advantage of creating indexes is to provide quick and efficient access to data. An index is a data structure that stores the values of one or more columns of a table in a sorted order, along with pointers to the corresponding rows in the table. An index helps to speed up queries thatsearch, filter, sort, or join data based on the indexed columns, as it reduces the number of disk accesses or scans required to locate the desired data. An index also helps to enforce uniqueness or referential integrity constraints on the indexed columns. The other options are either not true or not relevant for this purpose. For example, an index does not help with space allocation, as it consumes additional space in the database; an index does not reduce memory, as it may use memory for caching or buffering purposes; an index does not update the query plan, as it is an input or a factor for the query optimizer to generate the query plan. References: CompTIA DataSys+ Course Outline, Domain 1.0 Database Fundamentals, Objective 1.2 Given a scenario, execute database tasks using scripting and programming languages.

• Question 92:

  A database administrator wants to remove inactive customers from a database. Which of the following statements should the administrator use?

  

  A. Option A
  B. Option B
  C. Option C
  D. Option D
  A. Option A

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  Explanation/Reference:

  The statement that the administrator should use to remove inactive customers from a database is option A. This statement uses the DELETE command to delete all the rows from the customer table where the status column is equal to 'inactive'. The other options either have syntax errors, use incorrect commands, or do not specify the condition correctly. References: CompTIA DataSys+ Course Outline, Domain 1.0 Database Fundamentals, Objective 1.2 Given a scenario, execute database tasks using scripting and programming languages.

• Question 93:

  Given the following customer table:

  

  Which of the following ORM snippets would return the ID, state, and country of all customers with the newest customers appearingfirst?

  

  A. Option A
  B. Option B
  C. Option C
  D. Option D
  C. Option C

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  Explanation/Reference:

  The ORM snippet that would return the ID, state, and country of all customers with the newest customers appearing first is option C. This snippet uses the select method to specify the columns to be returned, the order method to sort the results by ID in descending order, and the all method to fetch all the records. The other options either have syntax errors, use incorrect methods, or do not sort the results correctly. References: CompTIA DataSys+ Course Outline, Domain 1.0 Database Fundamentals, Objective 1.2 Given a scenario, execute database tasks using scripting and programming languages.