MySQL SUM的总数COUNT

Question

Seat Type   Quantity left


Business        23
Economy         27
First           15

            Total quantity left : ?

DBMS = MySQL

我已经尝试了以下SQL来打印以上信息

$sql = "SELECT SeatType, COUNT(SeatType)AS quantity
              FROM  seat

              WHERE SeatAvailable = 'Yes'  
              GROUP BY SeatType
              ";

我如何总结剩余的总量（例如：23 + 27 + 25）？ 谢谢您的高级帮助...

Answer 1

SELECT  COALESCE(SeatType, 'Total quantity left') `Seat Type`, 
        COUNT(SeatType)AS quantity
FROM    seat
WHERE   SeatAvailable = 'Yes'  
GROUP   BY SeatType WITH ROLLUP

• SQLFiddle演示
• GROUP BY修饰符

Answer 2

像这样：

select sum(quantity_left) SeatsRemaining
from etc