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Questions and Answers
What is the data type of the returned values when both component queries select values of data type VARCHAR2?
What is the data type of the returned values when both component queries select values of data type VARCHAR2?
- DATE
- VARCHAR2 (correct)
- CHAR
- NUMBER
In the example SELECT statements provided, what is displayed for the 'location' column?
In the example SELECT statements provided, what is displayed for the 'location' column?
- department ID
- NULL (correct)
- hire date
- location ID
What does the UNION operator do when used between the SELECT statements in the examples?
What does the UNION operator do when used between the SELECT statements in the examples?
- Concatenates the results from both queries
- Combines the results and removes duplicate rows (correct)
- Performs an inner join operation on the results
- Only displays results from the second query
What is the purpose of the COLUMN a_dummy NOPRINT statement in the provided SQL example?
What is the purpose of the COLUMN a_dummy NOPRINT statement in the provided SQL example?
How many operators are there in SET Operators as mentioned in the text?
How many operators are there in SET Operators as mentioned in the text?
What determines the data type of the returned values when both component queries select values of data type VARCHAR2?
What determines the data type of the returned values when both component queries select values of data type VARCHAR2?
What is displayed when using the UNION operator to combine the SELECT statements for all employees?
What is displayed when using the UNION operator to combine the SELECT statements for all employees?
What is the purpose of using the SET Operators mentioned in the text?
What is the purpose of using the SET Operators mentioned in the text?
What does the 'ORDER BY a_dummy' clause achieve in the SQL example provided?
What does the 'ORDER BY a_dummy' clause achieve in the SQL example provided?
Which statement accurately describes the UNION operator?
Which statement accurately describes the UNION operator?
In the example SELECT statements, what is the purpose of 'TO_NUMBER(null)' and 'TO_DATE(null)'?
In the example SELECT statements, what is the purpose of 'TO_NUMBER(null)' and 'TO_DATE(null)'?
'COLUMN a_dummy NOPRINT' is used for what purpose?
'COLUMN a_dummy NOPRINT' is used for what purpose?
'SELECT department_id, location, hire_date FROM employees UNION...' retrieves which columns?
'SELECT department_id, location, hire_date FROM employees UNION...' retrieves which columns?
'UNION' is an operator that performs what function between datasets?
'UNION' is an operator that performs what function between datasets?
