在日期範圍之間的mysql變量避免重複

Question

我不確定它是否可能，但是我可以使用set vars來避免在以下查詢上重複日期範圍嗎？那麼我只會聲明TY和LY一次並在查詢中重用？

// ThisYear -- '2013-02-04 00:00:00' AND '2013-02-10 23:59:59' 
// LastYear -- '2012-02-06 00:00:00' AND '2013-02-12 23:59:59' 

SELECT 
    count(*) as total_num_bookings, 

    SUM(if(book_date BETWEEN '2013-02-04 00:00:00' AND '2013-02-10 23:59:59', 1, 0)) AS num_bookings_ty, 
    SUM(if(book_date BETWEEN '2012-02-06 00:00:00' AND '2012-02-12 23:59:59', 1, 0)) AS num_bookings_ly, 
    sj.pu_country 

FROM 
    pc_tech.sales_journal_default sj 

WHERE (book_date BETWEEN '2013-02-04 00:00:00' AND '2013-02-10 23:59:59') OR (book_date BETWEEN '2012-02-06 00:00:00' AND '2012-02-12 23:59:59') 
group by pu_country 
order by total_num_bookings DESC 
LIMIT 25; 

Answer 1

是：

SET @ThisYear1='2013-02-04 00:00:00', @ThisYear2='2013-02-10 23:59:59' 
SET @LastYear1='2012-02-06 00:00:00', @LastYear2='2013-02-12 23:59:59' 

SELECT 
    count(*) as total_num_bookings, 

    SUM(if(book_date BETWEEN @ThisYear1 AND @ThisYear2, 1, 0)) AS num_bookings_ty, 
... 

編輯

或者使用準備好的語句：

SET @ThisYear="'2013-02-04 00:00:00' AND '2013-02-10 23:59:59'"; 
SET @LastYear="'2012-02-06 00:00:00' AND '2013-02-12 23:59:59'"; 

SET @sql = CONCAT("SELECT count(*) as total_num_bookings, SUM(if(book_date BETWEEN ", @ThisYear, ", 1, 0)) AS num_bookings_ty, ..."); 
PREPARE stmt from @sql; 
EXECUTE stmt; 
... 
DEALLOCATE PREPARE stmt;