Saturday, October 15, 2016

08 Introduction to Functions

1.  For each task, choose whether a single-row or multiple row function would be most appropriate:
a. Showing all of the email addresses in upper case letters- single row
b. Determining the average salary for the employees in the sales department- multiple row
c. Showing hire dates with the month spelled out (September 1, 2004)- single row
d. Finding out the employees in each department that had the most seniority (the earliest hire date)- multiple row
e. Displaying the employees’ salaries rounded to the hundreds place- single row
f. Substituting zeros for null values when displaying employee commissions. - Single row

2.  The most common multiple-row functions are: AVG, COUNT, MAX, MIN, and SUM. Give your own definition for each of these functions.
AVG- finds the average value of in group of rows.
COUNT- counts the number of rows input
MAX- finds highest value in the group of rows
MIN- finds lowest value in the group of rows.
SUM- Adds values in group of rows. 

3.  Test your definitions by substituting each of the multiple-row functions into this query.
FROM employees
Write out each query and its results.
SELECT AVG(salary)
FROM employees;
FROM employees;
SELECT MAX(salary)
FROM employees;
SELECT MIN(salary)
FROM employees;
SELECT SUM(salary)
FROM employees;


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