Basic SQL Chapter 4

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Questions and Answers

What is the main reason for the commercial success of relational databases?

  • Relational database concept
  • ANSI SQL standard
  • SQL language (correct)
  • System R with Sequel

What is the year when E.Codd developed relational database concept?

  • 1979
  • 1974
  • 1970 (correct)
  • 1986

What is SQL used for?

  • Only for data definitions
  • For both data definitions and queries, and updates (correct)
  • Only for queries and updates
  • Only for security

What is the year when Oracle marketed the first relational DB with SQL?

<p>1979 (B)</p>
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What is the acronym for Structured Query Language?

<p>SQL (D)</p>
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What is the purpose of query optimization in query processing?

<p>To select an efficient query evaluation plan (C)</p>
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What is the output of the parsing and translation step in query processing?

<p>A parse tree (D)</p>
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What is the purpose of the evaluation step in query processing?

<p>To execute the query and return the answers (D)</p>
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What is the function of the parser in query processing?

<p>To verify the query is syntactically correct and construct a parse tree (A)</p>
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What is the purpose of relational algebra in query processing?

<p>To represent the query in a formal language (C)</p>
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What is an advantage of using relational algebra in query processing?

<p>It provides a formal language for representing queries (D)</p>
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What is the purpose of the CREATE DOMAIN construct in SQL?

<p>To declare a customized data type (D)</p>
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Which of the following is a characteristic of the TIMESTAMP data type?

<p>Includes the DATE and TIME fields, plus a minimum of six positions for decimal fractions of seconds (A)</p>
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What is the purpose of the INTERVAL data type?

<p>To specify a relative value that can be used to increment or decrement an absolute value of a date, time, or timestamp (B)</p>
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What is the function of the LIKE comparison operator?

<p>To perform string pattern matching (D)</p>
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What is the purpose of the EXCEPT operator in the given SQL query?

<p>To retrieve data from two tables except for common rows (B)</p>
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What is the purpose of the UNION operator in the given SQL query?

<p>To combine the results of two SELECT statements (D)</p>
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What is the purpose of the underscore (_) in pattern matching?

<p>To replace a single character (A)</p>
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What is the function of the IS NULL operator?

<p>To check if an attribute value is NULL (D)</p>
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What is the purpose of the BETWEEN operator?

<p>To check if a value is within a range (B)</p>
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What is the purpose of the IN operator?

<p>To check if a value is in a list of values (C)</p>
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What is the purpose of the ORDER BY clause?

<p>To sort the rows in a particular order (A)</p>
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What is the purpose of the SELECT statement with the FROM and WHERE clauses?

<p>To retrieve data from a table based on conditions (A)</p>
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What is the purpose of the INSERT command in SQL?

<p>To add tuples to a relation (D)</p>
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What is the minimum number of clauses required in a SQL query?

<p>Two (B)</p>
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What is the function of the FROM clause in a SQL query?

<p>To specify the relation(s) to retrieve data from (C)</p>
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What is the purpose of the ORDER BY clause in a SQL query?

<p>To sort data in a specific order (A)</p>
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What are the three commands used to modify a database?

<p>INSERT, DELETE, UPDATE (D)</p>
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What is the purpose of the second form of the INSERT command?

<p>To insert data into a relation with explicitly specified attribute names (A)</p>
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