Update field through relationship?

[Database Administrator]

I have a two-table relationship and I want to get rid of one table.

I have a table of surveys, where each row is related to one row in a
table of access codes. These are the relevant fields:

Surveys.access_code_id
AccessCodes.id
AccessCode.valid_date

We are moving to a new method of access validation, so we don't need
the table of AccessCodes anymore. I want to add the field
Surveys.valid_date, and update the value with the appropriate value
from the AccessCodes table, before I delete it.

So I want to do something like

UPDATE Surveys SET Surveys.valid_date = SELECT valid_date FROM
AccessCodes WHERE AccessCodes.id = Surveys.access_code_id

Is this the proper syntax? I'm hesitant to play around with UPDATE
queries!

[Database Administrator]

On Nov 14, 12:52*pm, lawpoop wrote:

>
> So I want to do something like
>
> UPDATE Surveys SET Surveys.valid_date = SELECT valid_date FROM
> AccessCodes WHERE AccessCodes.id = Surveys.access_code_id
>
> Is this the proper syntax? I'm hesitant to play around with UPDATE
> queries!

I did some testing with some test tables, and this works:

UPDATE Surveys SET survey_date = ( SELECT `date` FROM AccessCodes
WHERE AccessCodes.id = Surveys.access_code_id );