如何将具有相同PK的项目中的数据一起添加

Question

这是我的SQL查询

SELECT product.productNum, product.description, prod_location.quantityOnHand 
FROM product 
INNER JOIN prod_location ON prod_location.productNum = product.productNum

，这是输出。

productNum | description | quantityOnHand
660        | Reflex Paper| 100
660        | Reflex Paper| 95
660        | Reflex Paper| 64
661        | Window Clean| 200
661        | Window Clean| 67
661        | Window Clean| 38
662        | Acid        | 300
662        | Acid        | 100
662        | Acid        | 100
663        | Pens        | 400
663        | Pens        | 200
663        | Pens        | 153
664        | Door Mats   | 200

如何获取它，以便将每个productNum的quantmentOnHand相加在一起，所以它只是说反光纸而不是3行

productNum | description | quantityOnHand
660        | Reflex Paper| 259
661        | Window Clean| 305
662        | Acid        | 500
663        | Pens        | 753
664        | Door Mats   | 200

非常感谢您的帮助。

Answer 1

类似这样的东西

SELECT product.productNum, product.description, SUM(prod_location.quantityOnHand) as quantityOnHand
FROM product 
INNER JOIN prod_location ON prod_location.productNum = product.productNum
GROUP BY product.productNum

Answer 2

如果product表和prod_locatoin表之间的关系是一对多的。并且prduct.productNum是唯一的

SELECT product.productNum, product.description, SUM(prod_location.quantityOnHand) as quantityOnHand
FROM product 
INNER JOIN prod_location ON prod_location.productNum = product.productNum
GROUP BY product.productNum