Multiply 2 values from 2 different tables

I'm trying to multiply value X by value Y with SQL. Value X is located in table A and B is located in table B. I couldn't find the answer for this.

Table Transactions

ID Transaction_ID Total_Amount
1  001            1200
2  002            1500
3  003            1600

Table Rates

ID Currency_Name Exchange_Rate
1  AUD           1.5
2  SEK           2.0
3  PLN           3.0

The question I'm trying to answer is:

What is the Total_Amount for transaction 001 in SEK (Swedish Crown). So I need to multi开发者_开发百科ply 1200 * 2.0 and display the result.

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Edited based on added info

SELECT Total_Amount * Exchange_Rate AS Value 
FROM Transactions, Rates 
WHERE Rates.Currency_Name = 'Sek' and Transaction_id = 001

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To answer your question:

What is the Total_Amount for transaction 001 in SEK (Swedish Crown). So I need to multiply 1200 * 2.0 and display the result.

Use:

SELECT ID, Transaction_ID, Total_Amount, Total_Amount*(SELECT Exchange_Rate from Rates where Currency_Name='SEK') 
FROM TRANSACTIONS
WHERE TRANSACTION_ID='001'

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This should work, depending on your table structure :

select table1.x * table2.y
from table1, table2;

But I actually doubt that this is really what you want to do, if you provide more information, we could give you a much better answer. Please provide table structure and you're real goal !

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how about this:

select a.x*b.y from tableA a, tableB b