通过匹配另一个表中主键以外的列来更新外键

Question

I am trying to update the FooID column in Table_One with a FooID from table two. I have the primary key for the rows I want to update for Table One , but I need to get that ID from Table_Two where a given Description exists. So say I know that Table_One Primary_ID = 3 needs to have a FooID of 3, because FooID of Table_Two has a description of "Bar." What kind of SQL statement can I use to match the ID based on the value of the Description ?

Table_One

+-----------+---------+------+-----+---------+-------+
| Field     | Type    | Null | Key | Default | Extra |
+-----------+---------+------+-----+---------+-------+
| Primary_ID| int(11) | NO   | PRI | NULL    |       |
| Statement | text    | YES  |     | NULL    |       |
| FooID     | int(11) | YES  | MUL | NULL    |       |
+-----------+---------+------+-----+---------+-------+

Table_Two

+------------+--------------+------+-----+---------+----------------+
| Field      | Type         | Null | Key | Default | Extra          |
+------------+--------------+------+-----+---------+----------------+
| FooID      | int(11)      | NO   | PRI | NULL    | auto_increment |
| Description| varchar(140) | NO   |     | NULL    |                |
+------------+--------------+------+-----+---------+----------------+

So far I have tried a few things similar to:

UPDATE Table_one
INNER JOIN Table_Two ON (Table_One.FooID = Table_Two.FooID AND Table_Two.Description =     'Bar')
SET ksa.FooID = competency.FooID;

As well as:

UPDATE Table_One
SET
`FooID` = [SELECT FooID FROM Table_Two]
WHERE `Table_Two`.`Description` = 'Bar';

The first attempt returned zero results, and the second attempt kept saying the the column in Table_Two does not exist. I tried a few other things as well but nothing has worked. These were the closest I came to something working.

Answer 1

If you want to update a known record from table one with a value that you want to get from a known record in table two, then you don't need anything too complex. You could do this by fetching the value from table two in one query, and then updating the record in table one in a second. You can do this in one query though by using a subquery as a scalar operand .

UPDATE Table_One SET FooID = 
    (SELECT FooID FROM Table_Two WHERE Description = 'Bar')
    WHERE Primary_ID = 3;

Answer 2

The set in the first alternative seems to be wrong:

UPDATE Table_one
INNER JOIN Table_Two ON (Table_One.FooID = Table_Two.FooID AND Table_Two.Description =    'Bar')
SET ksa.FooID = competency.FooID;

Have you tried this:

UPDATE Table_one
INNER JOIN Table_Two ON (Table_One.FooID = Table_Two.FooID AND Table_Two.Description =        'Bar')
SET FooID = Table_Two.FooID;

?