Question

I am having trouble writing a sql query and I was hoping that someone may be able to help me out.
Here’s what I want my query to do:

1. Take the “prod_value” column from the “product” table
2. Multiply a constant (assume the number 2) times the “worth” column on the “value” table that corresponds to the one-to-one relationship between value <-> product.
3. Update the “prod_value” column in the “product” table to the new updated value.

For example…
Here’s the tables:
value

  id     |      worth       |     product_id     |
   1     |         10       |         1          |

product (before)

   id    |     name        |        prod_value    |
   1     |    product1     |           100        |

and assume constant = 2.

Then what I want after I run the query is the following:

product (after)

   id    |     name        |        prod_value    |
   1     |    product1     |           120        |

The 120 comes from 100 (previous value) + 2*10

I was hoping to have this done with one single query, is this even possible?
If anyone can help me I would be very grateful!
Thanks 🙂

Answer 1

UPDATE `product`
INNER JOIN `value` ON `product`.`id`= `value`.`product_id`
SET `product`.`prod_value` = `product`.`prod_value` + 2* `value`.`worth`