D492 Data Analytics Applications - Set 4 - Part 3

Correct Answer: LIKE

The LIKE operator is used to select rows that match a specified pattern, often using wildcards such as % or _. IN checks for values within a list, BETWEEN selects values within a range, and EXISTS checks for the existence of rows in a subquery.

Correct Answer: CURDATE()

The CURDATE() function returns the current date in SQL. NOW() returns both the current date and time, TIME() returns only the time, and DATE() extracts the date part from a timestamp.

Correct Answer: ALTER TABLE

The ALTER TABLE statement is used to modify the structure of an existing table, such as adding, removing, or modifying columns. CREATE TABLE creates a new table, DELETE removes rows, and INSERT adds new rows.

Correct Answer: Removes duplicate rows from the result set

The DISTINCT keyword eliminates duplicate rows from the result set, ensuring that only unique rows are returned. It does not remove rows based on a condition or sort the result set.

Correct Answer: AVG()

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

Correct Answer: ALTER TABLE

The ALTER TABLE statement is used to add a new column to an existing table. CREATE TABLE is used to create a new table, INSERT INTO adds new rows, and UPDATE modifies existing rows.

Correct Answer: HAVING

The HAVING clause filters groups after they have been aggregated, typically used with GROUP BY. WHERE filters rows before aggregation, while ORDER BY sorts the result set and LIMIT restricts the number of rows returned.

Correct Answer: A query that is nested inside another query

A subquery is a query that is nested inside another query, typically within the WHERE, FROM, or SELECT clauses. It is used to perform additional filtering or calculations within the main query.

Correct Answer: YEAR()

The YEAR() function extracts the year from a date. CURDATE() returns the current date, DATE() formats a date, and EXTRACT() can be used to extract specific parts of a date, such as the year, month, or day.

Correct Answer: All rows from the left table and the matching rows from the right table

A LEFT JOIN returns all rows from the left table and the matching rows from the right table. If there is no match, NULL values are returned for columns from the right table.