sql help:如何一起添加数量？

Question

基本上这个代码返回正确的信息,但我需要将数量一起添加以带回一条记录.有没有办法做到这一点？

select category.category_name, (equipment.total_stock-equipment.stock_out) AS Current_Stock, equipment.stock_out
from
EQUIPMENT,
CATEGORY
WHERE  EQUIPMENT.CATEGORY_ID = CATEGORY.CATEGORY_ID
and category.category_name = 'Power Tools' 

Answer 1

您想使用SUM函数和GROUP BY子句.

select category.category_name, SUM((equipment.total_stock-equipment.stock_out)) AS Current_Stock, SUM(equipment.stock_out) as stock_out
from EQUIPMENT, CATEGORY 
WHERE EQUIPMENT.CATEGORY_ID = CATEGORY.CATEGORY_ID and category.category_name = 'Power Tools'
GROUP BY Category.Category_Name