Task: Text to Code
Input (English): Step 1: For each row in Employee table, find the corresponding rows in Customer table.
Step 2: find the number of rows of each value of SupportRepId in the results of step 1.
Step 3: find Employee's LastName in the results of step 1 whose corresponding value in step 2 is less than or equals 20
Output (English): SELECT T2.LastName FROM Customer AS T1 JOIN Employee AS T2 ON T1.SupportRepId = T2.EmployeeId GROUP BY T1.SupportRepId HAVING Count ( * ) < = 20