MYSQL Select Statment with Modification to tuple values

I have the following table:

bar_id, bar_name, subscription_id_fk, sub_name

eg:

1, Hard Rock, 2, Gold
2, TGIF, 1, Free

Now I need and SQL to extract this table, b开发者_如何学Pythonut where sub_name = Gold, I need to double the subscription_id_fk.

Can you please help ?

Edit: I need this value to be only changed in the result of the SQL statment

SELECT IF(sub_name = 'Gold', subscription_id_fk * 2, subscription_id_fk) as fk 
FROM my_table 

Are you looking for something as simple as

SELECT (subscription_id_fk * 2) as double_sif
FROM table
WHERE sub_name = 'Gold'

As you accepted this answer a few comments

• SELECT statements never change anything in the database, for that you need UPDATE, INSERT or DELETE (at least read wikipedia article on SQL)
• the name of the field suggests that it is a foreign key to another table and even though it is possible, normally multiplying keys don't make any sense

This may help you.

So, According to the link you try,
select subscription_id_fk * 2 from table where sub_name = 'Gold'

I hadn't try it practically.I just find it on internet. So, Try it.

Ok, if you need all rows, but only "Gold"-ones with doubled keys, you could use

SELECT 
    GREATEST(t.subscription_id_fk, IFNULL(t2.subscription_id_fk,0)) AS subscription_id_fk, 
    bar_id, 
    bar_name, 
    sub_name
FROM table AS t
LEFT JOIN (
    SELECT (subscription_id_fk * 2) AS subscription_id_fk, 
        id 
    FROM table t2 
    WHERE sub_name ="Gold") AS t2
ON (t.id = t2.id)

Maybe I don't understand the question, but this looks like a simple update to me:

UPDATE table 
SET subscription_id_fk = (subscription_id_fk * 2) 
WHERE sub_name = "Gold"