我试图在内连接的子查询中获得12列（在同一个表中）的总和。 这是我的架构的链接：
我试图使用的查询是：
SELECT
`inventory`.`part_number`,
`inventory`.`qty`,
`inventory`.`description`,
`reorder`.`reorder_point` * '1' `point`,
`inventory`.`cost`,
`vendor`.`name` AS `vendor_name`, SELECT (SUM(`saleshistory`.`Sales_1_Month_Prior`)+SUM(`saleshistory`.`Sales_2_Month_Prior`)+SUM(`saleshistory`.`Sales_3_Month_Prior`)+SUM(`saleshistory`.`Sales_4_Month_Prior`)+SUM(`saleshistory`.`Sales_5_Month_Prior`)+SUM(`saleshistory`.`Sales_6_Month_Prior`)+SUM(`saleshistory`.`Sales_7_Month_Prior`)+SUM(`saleshistory`.`Sales_8_Month_Prior`)+SUM(`saleshistory`.`Sales_9_Month_Prior`)+SUM(`saleshistory`.`Sales_10_Month_Prior`)+SUM(`saleshistory`.`Sales_11_Month_Prior`)+SUM(`saleshistory`.`Sales_12_Month_Prior`) AS TTL
FROM `inventory`
LEFT JOIN `reorder` ON `inventory`.`part_number` = `reorder`.`part_number`
LEFT JOIN `vendor` ON `inventory`.`vendor` = `vendor`.`vendor_id`
INNER JOIN `saleshistory` ON `saleshistory`.`location` = `inventory`.`location` AND `saleshistory`.`part_number` = `inventory`.`part_number`
WHERE `inventory`.`qty` <= `reorder`.`reorder_point`
AND `inventory`.`location` = '99'
AND `reorder`.`reorder_point` != '0'
GROUP BY `inventory`.`part_number`
ORDER BY `vendor`.`name` ASC
使用此查询时，它会返回所有记录的所有值，而不仅仅是行。