SQL query where() date's year is $year

Do NOT use YEAR(date) - this will calculate YEAR(date) for all dates, even for those, you never use. It will also make use of an index impossible - worst case on the DB layer.

Use

$sql="SELECT * FROM table WHERE `date` BETWEEN '$year-01-01' AND '$year-12-31'"

As a general rule: If you have the choice between a calculation on a constant and a calculation on a field, use the former.

Check out the YEAR() docs function for MySQL

SELECT * FROM table WHERE YEAR(date)=2012

select * from table where DATEPART(YEAR,[DATE])=2012