Mysql - selecting year from a unix timestamp

Question

I am using this:

SELECT FROM_UNIXTIME(my_unix_timestamp_column, '%Y') AS year FROM table_name WHERE year = 2009;

but it gives me an error:

Unknown column 'year' in 'where clause'SELECT FROM_UNIXTIME(my_unix_timestamp_column, '%Y') AS year FROM table_name WHERE year = 2009

Both "my_unix_timestamp_column" and "table_name" are correct, i dont know why it gives me this!!!

I'm using PHP 5.3.0

Answer 1

I'm not quite sure whether this is due to YEAR being a reserved word in MySQL or because it wants you to do something along the lines of:

SELECT
  FROM_UNIXTIME(my_unix_timestamp_column, '%Y') AS year
FROM
  table_name
WHERE
  FROM_UNIXTIME(my_unix_timestamp_column, '%Y') = 2009;

Can't remember whether the last issue is only relevant to GROUPings :S

Answer 2

SELECT  FROM_UNIXTIME(my_unix_timestamp_column, '%Y') AS `year`
FROM    table_name
HAVING  `year` = 2009

Unlike WHERE clause, HAVING clause can reference the SELECT clause aliases.

More index efficient way would be:

SELECT  FROM_UNIXTIME(my_unix_timestamp_column, '%Y') AS `year`
FROM    table_name
WHERE   my_unix_timestamp_column >= UNIX_TIMESTAMP('2009-01-01')
        AND my_unix_timestamp_column < UNIX_TIMESTAMP('2010-01-01')