What's the best way to perform an UPDATE with JOIN in SQL Server?

Data and Databases
1

I’m working on a database project and need some help with SQL Server. I’ve got two tables: sales_data and user_details. Here’s what they look like:

sales_data:
- record_id (int)
- user_detail_id (int)
- asset_id (int)

user_details:
- detail_id (int)
- asset_id (int)

The sales_data.asset_id has the right value to update user_details.asset_id. I’m thinking I need to use a JOIN to make this work, but I’m not sure how to structure the query.

Can anyone show me how to write an UPDATE statement that uses a JOIN to update the asset_id in the user_details table based on the matching records in sales_data? I’m pretty new to complex SQL queries, so a simple explanation would be really helpful. Thanks!

2

hey there finn! i’ve had to do something similar before. you can use an UPDATE with INNER JOIN like this:

UPDATE ud
SET ud.asset_id = sd.asset_id
FROM user_details ud
INNER JOIN sales_data sd ON ud.detail_id = sd.user_detail_id

this should update the asset_id in user_details. hope it helps!

3

The most efficient approach for your scenario would be to use an UPDATE statement with a JOIN clause. This method allows you to update the user_details table based on matching records in the sales_data table in a single operation. Here’s the query structure:

UPDATE ud
SET ud.asset_id = sd.asset_id
FROM user_details ud
INNER JOIN sales_data sd ON ud.detail_id = sd.user_detail_id

This query updates the asset_id in user_details with the corresponding asset_id from sales_data where the detail_id matches the user_detail_id. It’s concise, performs well, and doesn’t require creating temporary tables or CTEs. Remember to test this query on a small dataset or in a development environment before running it on your production database.

4

hey finn! have u considered using a CTE for this? it might make things clearer. something like:

WITH UpdateCTE AS (
SELECT ud.detail_id, sd.asset_id
FROM user_details ud
JOIN sales_data sd ON ud.detail_id = sd.user_detail_id
)
UPDATE user_details
SET asset_id = UpdateCTE.asset_id
FROM UpdateCTE
WHERE user_details.detail_id = UpdateCTE.detail_id

what do you think? Does this approach make sense to u?