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Function COUNT
Function AVG
Functions SUM, MAX, MIN


As you may already suspect, COUNT(DISTINCT expression) can be also used together with GROUP BY. Try it out in the exercise below.


The rate per word is the price divided by the number of words. Show translator id together with number of distinct rates per word he used in his projects. Name the second column rates_no.

Stuck? Here's a hint!

To obtain the rate per word, use CAST(price AS numeric)/words.