使用来自第三个表的共享ID，使用来自另一个表的数据的空列更新表

Question

Hi Guys new to this and need pointed in the right direction.

DB1 product_description [product_id, name, description]

*DB1.product_description.product_id is linked to category_id in a separate product_to_category_id table. category_id in table1 == cat_id in DB2.Inventory

  DB1  product_description

------------------------------------------------------
| product_id     | name          |  description       |
-------------------------------------------------------
| 999            | product999    | description text   |
| 1000           | product1000   |                    |
| 1001           | product1001   |                    |
| 2000           | product2000   |                    |
-------------------------------------------------------

DB2 Inventory [productId, name, description, cat_id]

DB2
Inventory
------------------------------------------------------------------
| productId     | name          |  description       | cat_id    |
-----------------------------------------------------------------
| 999            | product999    | description text  | 236       |
| 1000           | product1000   | description text2 | 237       |
| 1001           | product1001   | description text3 | 237       |
| 2000           | product2000   | description text4 | 456       |
-----------------------------------------------------------------


DB1
product_to_category
---------------------------------
| product_id     | category_id   |
---------------------------------
| 999            | 236           |
| 1000           | 237           |
| 1001           | 237           |
| 2000           | 456           |
---------------------------------

I am looking to copy the "description" data from DB2 and place it into the "description" in DB1 preferably using WHERE cat_id >=237 <=456

I was hoping to use the category id because I can move products over and insert meta dat at the same time. cat_id is a collection of products around 200 or using the productId but I would need to update the other fields separately

UPDATE DB1.product_description
SET description = (SELECT description
FROM DB2.Inventory
WHERE `cat_id` =2616);

it gives the error #1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'SET description = (SELECT description FROM DB2.Inventory WHEREcat_id=2616)' at line 2

removed the comma thanks strawberry ;) now get the error;

#1242 - Subquery returns more than 1 row

I have 30,000 products listed with descriptions, but need to integrate another 2000 products into the database, without disturbing products that have data already in the description field.

I have tried various post on this site before posting but can't figure out how to use the cat_id form the separate table. Or even if its possible. If someone would be kind enough to point out where I'm going wrong i would be grateful. I have spent the last three days trying to get the description field filled but with no joy after viewing tons of posts on the forum

Thanks again

HTT

Answer 1

Please try the following on your test environment:

UPDATE 
  DB1.product_description
  INNER JOIN DB2.Inventory
     ON DB2.Inventory.productId = DB1.product_description.product_id
SET 
  DB1.product_description.description = DB2.Inventory.description
WHERE 
  DB2.Inventory.cat_id = 2616;  

/* 
   or for the range of records:  
   WHERE (DB2.Inventory.cat_id >= 237 AND DB2.Inventory.cat_id <= 456)
*/

I think Mr @Jay Blanchard pointed to the right direction.

Hope it may help at least a little.