Joining two tables without a common column but using another table connected to both

Question

I have three tables in Mysql

table A-> uid, itemType, balance,orderType
table B-> orderId, itemType, qty
table C-> uid,orderId

I need to get (balance-qty) for every uid:orderIdcombination for specific type of item. How can I connect table A and table B if they have no common column to join on. But both of them are connected to table C.

You can join all three in one SELECT statement. You'd have two JOIN clauses. See [SQL inner join more than two tables](https://stackoverflow.com/questions/14995000/sql-inner-join-more-than-two-tables). — lurker, Apr 04 '19 at 18:59

score 0 · Accepted Answer · answered Apr 04 '19 at 19:03

0

With joins between the 3 tables:

select a.uid, a.balance, b.qty
from tablea a 
inner join tablec c on c.uid = a.uid
inner join tableb b on b.orderid = c.orderid
where a.itemtype = ?

You can add more columns if you need them.

answered Apr 04 '19 at 19:03

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Joining two tables without a common column but using another table connected to both

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