D492 Data Analytics Applications - Set 3 - Part 3

Correct Answer: SQRT()

The SQRT() function returns the square root of a number. ROUND() rounds a number, POW() raises a number to a power, and LOG() calculates the natural logarithm.

Correct Answer: An index on the primary key column of a table

A PRIMARY INDEX is an index on the primary key column of a table, used to improve query performance. It is not automatically created and does not enforce referential integrity or contain unique values unless specified.

Correct Answer: CONCAT()

The CONCAT() function is used to concatenate multiple values into a single string. SUBSTRING() extracts a portion of a string, LENGTH() returns the length of a string, and TRIM() removes spaces.

Correct Answer: MAX()

The MAX() function returns the maximum value in a column. MIN() returns the minimum value, COUNT() returns the number of rows, and AVG() returns the average value.

Correct Answer: To link rows between two tables

A FOREIGN KEY links rows between two tables by referencing a primary key in another table. It is used to maintain relationships between tables.

Correct Answer: HAVING

The HAVING clause filters rows based on the result of an aggregate function, such as SUM() or COUNT(). WHERE filters rows before aggregation, while GROUP BY groups rows and ORDER BY sorts them.

Correct Answer: ALTER TABLE

The ALTER TABLE statement is used to modify the structure of an existing table, including adding or removing columns. DROP COLUMN is not a valid standalone command, and TRUNCATE removes rows but retains the table structure.

Correct Answer: The number of rows in a result set

The COUNT() function returns the number of rows in a result set. SUM() adds numeric values, AVG() calculates the average, and MAX() returns the highest value in a column.

Correct Answer: WHERE

The WHERE clause is used to filter rows based on a specific condition. It is commonly used before the rows are grouped or sorted by GROUP BY or ORDER BY.

Correct Answer: To calculate the average value of a column

The AVG() function calculates the average value of a column. MAX() returns the highest value, COUNT() returns the number of rows, and SUM() adds up numeric values.