Count Events/year in SQL - mysql

Question

I have a list of events that have a date. I'm trying to count how many events take place in the current year, and 5 years on either side (regardless of whether any events took place) in mySQL using simple joins, selects, etc (no subqueries) in a single statement.
I have a table that produces the years and the number of events in that year, but am having problems when the year has no events taking place

Answer 1

Look into date functions on mysql http://dev.mysql.com/doc/refman/5.1/en/date-and-time-functions.html#function_datediff
You can use datediff which will give you difference in days. Ex;
WHERE abs(datediff(now(), event_date)) < 365*5
or dateadd(), if your event dates are timestamps, use timestampdiff()
Sample query
SELECT count(*) FROM mytable
WHERE abs(datediff(now(), event_date)) < 365*5
UPDATE
based on some of the comments I've read here, here's a query for you
SELECT year(event_date) as event_year, count(event_date)
FROM mytable
WHERE
abs(datediff(now(), event_date)) < 365*5
GROUP by year(event_date)
Feel free to adjust 5 in (365 * 5) for different range
UPDATE 2
This is NOT very pretty but you can try this with pure mysql. You can also modify this to be a stored proc if necessary:
SET #y6 = year(now());
SET #y5 = #y6-1;
SET #y4 = #y5-1;
SET #y3 = #y4-1;
SET #y2 = #y3-1;
SET #y1 = #y2-1;
SET #y7 = #y6+1;
SET #y8 = #y7+1;
SET #y9 = #y8+1;
SET #y10 = #y9+1;
SET #y11 = #y10+1;
CREATE TEMPORARY TABLE event_years (event_year int not null);
INSERT INTO event_years SELECT #y1;
INSERT INTO event_years SELECT #y2;
INSERT INTO event_years SELECT #y3;
INSERT INTO event_years SELECT #y4;
INSERT INTO event_years SELECT #y5;
INSERT INTO event_years SELECT #y6;
INSERT INTO event_years SELECT #y7;
INSERT INTO event_years SELECT #y8;
INSERT INTO event_years SELECT #y9;
INSERT INTO event_years SELECT #y10;
INSERT INTO event_years SELECT #y11;
SELECT ey.event_year , (SELECT count(event_date) from mytable where year(event_date) = ey.event_year)
from event_years ey;
temporary table will get dropped by itself after your connection is closed. If you add DROP TABLE after SELECT, you might not get your results back.

Answer 2

did you try to use join left?
MODIFIED:
SELECT tleft.YEARS, COUNT(tright.EVENTS)
FROM ONLY_YEARS tleft LEFT JOIN TABLE1 tright
ON (tleft.YEARS = tright.YEARS)
GROUP BY tleft.YEARS;
With that modification, you need to point to a table that holds all the years (ONLY_YEARS), maybe a dummy table with one column that goes from 1990 to 2020...
Left join optimization for MySQL link

Answer 3

To select a count of events that happened between two years, grouped by years, the following sql should suffice:
select year(event.date), count(*) from event where event.date >= '2006' and event.date <= '2016' group by year(event.date);
However, if no events occurred in a year, no result will be returned for it.
Databases are not really designed for such dynamic things and I'd suggest such logic should be put in a business (or possibly data-access) layer.