14 Questions
What is the data type of the returned values when both component queries select values of data type VARCHAR2?
VARCHAR2
In the example SELECT statements provided, what is displayed for the 'location' column?
NULL
What does the UNION operator do when used between the SELECT statements in the examples?
Combines the results and removes duplicate rows
What is the purpose of the COLUMN a_dummy NOPRINT statement in the provided SQL example?
To hide the 'a_dummy' column when printing query results
How many operators are there in SET Operators as mentioned in the text?
2
What determines the data type of the returned values when both component queries select values of data type VARCHAR2?
The data type remains VARCHAR2
What is displayed when using the UNION operator to combine the SELECT statements for all employees?
employee_id, job_id, and 0
What is the purpose of using the SET Operators mentioned in the text?
To combine results from multiple queries
What does the 'ORDER BY a_dummy' clause achieve in the SQL example provided?
It sorts the result set in ascending order of a_dummy values
Which statement accurately describes the UNION operator?
UNION concatenates columns from different tables vertically
In the example SELECT statements, what is the purpose of 'TO_NUMBER(null)' and 'TO_DATE(null)'?
Converting NULL values to specific data types
'COLUMN a_dummy NOPRINT' is used for what purpose?
To hide the 'a_dummy' column from query results
'SELECT department_id, location, hire_date FROM employees UNION...' retrieves which columns?
'department_id', 'location_id', and 'hire_date'
'UNION' is an operator that performs what function between datasets?
'Concatenation'
Learn how to use the MINUS operator in SQL to find the records of employees who have not changed their jobs. Practice subtracting employee IDs from different tables and displaying the results of employees who have not changed their jobs.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
