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Questions and Answers
What is the purpose of aggregation functions in SQL?
What is the purpose of aggregation functions in SQL?
- To multiply values in a table
- To perform operations on groups of rows and return one result per group (correct)
- To divide values in a table
- To filter out specific rows from a table
In the given text, which attribute is used for grouping tuples in the aggregation process?
In the given text, which attribute is used for grouping tuples in the aggregation process?
- Salary
- Dno (correct)
- Bdate
- Employee Fname
What happens if no grouping attribute is specified in an aggregation function?
What happens if no grouping attribute is specified in an aggregation function?
- The aggregation function cannot be performed
- The whole table is treated as one group (correct)
- Rows with the same value for the grouping attribute are grouped together
- Each row is considered a separate group
Which of the following statements about aggregation functions in SQL is true?
Which of the following statements about aggregation functions in SQL is true?
What is the role of the 'Super_ssn' attribute in the provided text?
What is the role of the 'Super_ssn' attribute in the provided text?
When applying an aggregation function, which attributes survive in the result along with the grouping attributes?
When applying an aggregation function, which attributes survive in the result along with the grouping attributes?
What is the purpose of using aliases in SQL queries?
What is the purpose of using aliases in SQL queries?
How can aliases be specified in SQL?
How can aliases be specified in SQL?
What does a missing WHERE-clause in an SQL query indicate?
What does a missing WHERE-clause in an SQL query indicate?
In an SQL query, what is the purpose of retrieving first names for all employees?
In an SQL query, what is the purpose of retrieving first names for all employees?
How does adding a WHERE clause change the behavior of an SQL query?
How does adding a WHERE clause change the behavior of an SQL query?
What does using the FROM clause with multiple tables allow in SQL queries?
What does using the FROM clause with multiple tables allow in SQL queries?
How would you retrieve the names of department managers when using the assignment operator?
How would you retrieve the names of department managers when using the assignment operator?
What does the operation 'Result ← ϬSSN = MGRSSN (Employee, Department)' in the exercise refer to?
What does the operation 'Result ← ϬSSN = MGRSSN (Employee, Department)' in the exercise refer to?
How can you find all employees (SSN) who do not work on any project manually?
How can you find all employees (SSN) who do not work on any project manually?
What would be the correct way to retrieve the SSN of employees who are neither supervisors nor managers?
What would be the correct way to retrieve the SSN of employees who are neither supervisors nor managers?
In what scenario would you use the Rename operation as described in the text?
In what scenario would you use the Rename operation as described in the text?
What does the cross product operation involve when used between two tables?
What does the cross product operation involve when used between two tables?
What is the purpose of the SELECT statement in SQL?
What is the purpose of the SELECT statement in SQL?
What is the function of the WHERE clause in a SQL query?
What is the function of the WHERE clause in a SQL query?
How can SQL tables be constrained to be sets?
How can SQL tables be constrained to be sets?
What is the purpose of specifying PRIMARY KEY or UNIQUE attributes in SQL tables?
What is the purpose of specifying PRIMARY KEY or UNIQUE attributes in SQL tables?
In SQL, what does the DISTINCT option do in a query?
In SQL, what does the DISTINCT option do in a query?
What does the PREFIX TableName.AttributeName indicate in SQL?
What does the PREFIX TableName.AttributeName indicate in SQL?
What value does Sally see in the database if she executes her statements after (ins) but before the rollback?
What value does Sally see in the database if she executes her statements after (ins) but before the rollback?
What happens to the effects of a transaction if it executes ROLLBACK instead of COMMIT?
What happens to the effects of a transaction if it executes ROLLBACK instead of COMMIT?
What does SET TRANSACTION ISOLATION LEVEL allow within a transaction?
What does SET TRANSACTION ISOLATION LEVEL allow within a transaction?
In SERIALIZABLE isolation level, what does Sally see regarding Joe's transaction?
In SERIALIZABLE isolation level, what does Sally see regarding Joe's transaction?
What is the purpose of isolation levels in SQL transactions?
What is the purpose of isolation levels in SQL transactions?
How does the DBMS handle isolation levels concerning the visibility of transactions?
How does the DBMS handle isolation levels concerning the visibility of transactions?
