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=背景介绍 -tableSales表 -第一次查询(2013销售员销售总额) select salesName, sum(extendedPrice) as sumprice13 from tableSales where salesTime between '2013-01-01' and '2013-12-31' group by salesName -第二次查询(2014销售员销售总额) select sale

=>背景介绍

->tableSales表

->第一次查询(2013销售员销售总额)

select salesName, sum(extendedPrice) as sumprice13 from tableSales where salesTime between '2013-01-01' and '2013-12-31' group by salesName

->第二次查询(2014销售员销售总额)

select  salesName, sum(extendedPrice) as sumprice14 from tableSales where salesTime between '2014-01-01' and '2014-12-31' group by salesName

->如何获得销售员13、14年的销售总额？

A、首先，我想到的就是用union all，但不理想；

select salesName, sum(extendedPrice) as sumprice13, null as sumprice14 from tableSales where salesTime between '2013-01-01' and '2013-12-31' group by salesName
union all
select  salesName, null as sumprice13, sum(extendedPrice) as sumprice14 from tableSales where salesTime between '2014-01-01' and '2014-12-31' group by salesName

B最后，通过fredrickhu版主大大的指点，修改如下：

SELECT
    a.salesName, a.sumprice13, b.sumprice14
FROM
    (SELECT
        salesName, SUM(extendedPrice) AS sumprice13
     FROM
        tableSales
     WHERE
        salesTime BETWEEN '2013-01-01' AND '2013-12-31'
     GROUP BY
        salesName
      ) AS a
INNER JOIN
     (SELECT
        salesName, SUM(extendedPrice) AS sumprice14
      FROM
        tableSales
      WHERE
        salesTime BETWEEN '2014-01-01' AND '2014-12-31'
      GROUP BY
        salesName
      ) AS b
ON a.salesName=b.salesName
 

最后再次感谢fredrickhu大大！谢谢！..风雨兼程...