Update Rows Where the following conditions are true - sql

Question

I am attempting to overwrite a field value with the value from another table where a certain condition is true. I have mocked up my code below
Pseudocode:
Where an employee has the team Ops in old_data, get their new team from new_data and overwrite the team in old_data
My Code:
UPDATE old_data -- This has columns Employee, Latest_Team
SET
Latest_Team =
(select new_data.team
from new_data
left join old data
ON old_data.employee = new_data.employee
)
WHERE old_data.employee = 'Ops'
But this is returning the error:
Subquery returned more than 1 value. This is not permitted when the subquery follows =, !=, <, <= , >, >= or when the subquery is used as an expression.
I'm not sure where i am going wrong exactly

Answer 1

If you are looking for the team "ops", then your query has several issues:
You are filtering on the employee, not the team.
You have a typo in the inner from clause.
You want a correlated subquery.
So, I think you want:
UPDATE old_data -- This has columns Employee, Latest_Team
SET Latest_Team = (select nd.team
from new_data nd
where old_data.employee = nd.employee
)
WHERE od.latest_team = 'Ops';
------^ I think this is the filter you describe

Answer 2

Make sure that this query doesnt return anyting and your code will work
select new_data.team, count(*)
from new_data
left join old data WHERE old_data.employee = 'Ops'
group by new_data.team
having count(*) > 1
If you have more than one team per employee with Old_data.employee = 'Ops', sql wont know which to choose for that employee for the update

Answer 3

You got a typo in your join - "old data" should be "old_data".
Maybe this can help you: update columns values with column of another table based on condition
In your example it would be:
UPDATE old_data SET
Latest_Team = (SELECT new_data.team FROM new_data WHERE old_data.employee = new_data.employee LIMIT 1)
WHERE old_data.employee = 'Ops';