To answer this question, we need to understand what group functions are in the context of databases.
Group functions, also known as aggregate functions, are functions that perform calculations on a set of values and return a single value. These functions are commonly used in SQL queries to summarize data. Some examples of group functions include AVG(), SUM(), and MAX().
Let's go through each option to determine which one is not a group function:
Option A) avg( ) - This option is a group function. The AVG() function calculates the average value of a set of values.
Option B) sqrt( ) - This option is not a group function. The SQRT() function calculates the square root of a single value, not a set of values. Therefore, this is the correct answer.
Option C) sum() - This option is a group function. The SUM() function calculates the sum of a set of values.
Option D) max() - This option is a group function. The MAX() function returns the maximum value from a set of values.
Therefore, the correct answer is B) sqrt( ) because it is not a group function.