CODEWITHSUNDEEP
mysqlsqljoin
emd
emd

Reputation: 414

Optimize complicated SQL query

Apologies if this obvious, but I'm not great at SQL. I have several tables that all need to be joined, but one of the columns can be null.

I have this query:

select orders.ordnum, orders.tstamp, orders.sku, code, redeemed_order_num, null as redeemed_date, null as fullname
from customer_subscriptions orders
join bulk_codes codes
    on codes.bulk_order_id = orders.subscription_id
where (orders.sku="bulk-box" or orders.sku="bulk-book") and redeemed_order_num is null
union
select orders.ordnum, orders.tstamp, orders.sku, code, redeemed_order_num, redeemed_orders.date redeemed_date, customers.fullname
from customer_subscriptions orders
join bulk_codes codes
    on codes.bulk_order_id = orders.subscription_id
join customer_subscriptions redeemed_orders
    on codes.redeemed_order_num = redeemed_orders.ordnum
join customers
    on customers.cid = redeemed_orders.cid
where (orders.sku="bulk-box" or orders.sku="bulk-book")

The top select returns the top 9 rows and the bottom one returns one row.

Results: Screenshot of results

Is there any way to optimize?

The full schema is here: https://pastebin.com/FXGLetcV

Upvotes: 1

Views: 68

Answers (2)

Gordon Linoff
Gordon Linoff

Reputation: 1271023

I think you just need left join:

SELECT orders.ordnum, orders.tstamp, orders.sku, code,
       redeemed_order_num, redeemed_orders.date redeemed_date, customers.fullname
FROM customer_subscriptions orders JOIN
     bulk_codes codes
     ON codes.bulk_order_id = orders.subscription_id LEFT JOIN
     customer_subscriptions redeemed_orders
     ON codes.redeemed_order_num = redeemed_orders.ordnum LEFT JOIN
     customers
     ON customers.cid = redeemed_orders.cid
WHERE orders.sku IN ('bulk-box', 'bulk-book')

Upvotes: 2

Vijiy
Vijiy

Reputation: 1197

Below would be the query.

         Select orders.ordnum, orders.tstamp, orders.sku, code, redeemed_order_num, null as redeemed_date, null as fullname
           From customer_subscriptions orders
     Inner join bulk_codes codes 
             On codes.bulk_order_id = orders.subscription_id 
            And redeemed_order_num is null -- comment
Left outer join bulk_codes codes 
             On codes.bulk_order_id = orders.subscription_id
left outer join customer_subscriptions redeemed_orders 
             On COALESCE(codes.redeemed_order_num, 111111) = redeemed_orders.ordnum
left outer join customers 
             On customers.cid = redeemed_orders.cid
          where orders.sku='bulk-box' 
             Or orders.sku='bulk-book'

Inthe query given by you, first select would join only redeemed_order_num with null value and in second select there is join on redeemed_order_num, use coalesce or IFNULL function to replace the null value at in join condition

Upvotes: 1

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