Count number of times value appears in particular column in MySQL
Solution 1:
select email, count(*) as c FROM orders GROUP BY email
Solution 2:
SELECT column_name, COUNT(column_name)
FROM table_name
GROUP BY column_name
Solution 3:
Take a look at the Group by function.
What the group by function does is pretuty much grouping the similar value for a given field. You can then show the number of number of time that this value was groupped using the COUNT function.
MySQL Documentation
You can also use the group by function with a good number of other function define by MySQL (see the above link).
mysql> SELECT student_name, AVG(test_score)
-> FROM student
-> GROUP BY student_name;