To answer this question, we need to understand what SQL aggregate functions are.
SQL aggregate functions perform calculations on a set of values and return a single value as the result. They are used with the SELECT statement to perform operations such as calculating the average, sum, count, minimum, or maximum value of a column.
Let's go through each option to understand why it is correct or incorrect:
Option A) LEFT - This option is incorrect because LEFT is not an aggregate function. It is used to extract a specified number of characters from the left side of a string.
Option B) LEN - This option is incorrect because LEN is not an aggregate function. It is used to return the length of a string.
Option C) AVG - This option is correct because AVG is an aggregate function in SQL. It is used to calculate the average value of a column.
Option D) JOIN - This option is incorrect because JOIN is not an aggregate function. It is used to combine rows from two or more tables based on a related column between them.
The correct answer is C) AVG. This option is correct because AVG is a SQL aggregate function used to calculate the average value of a column.