LeetCode 183: Customers Who Never Order [SQL]

[@frederikmuller]

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[@julyw1291]

I like the second way, pretty straightforward and easy to understand.

[@mickyman753]

can you make a pattern sheet like , for similar pattern questions we can use this or that , like for this ques , pattern can be when we want first table elements not present in second then , doing left join make result table's 2nd table col null and can filter on null ,when we want to compare same column elements then self join is way to go........pattern like these would really help as when we lose touch to sql they can help us strike the inutition more

[@frederikmuller]

interesting idea

[@pimaniye41]

subquery method is far more useful in my opinion. thank you for the video. liked 👍

[@debashish_dutta]

3rd Approach: Using NOT EXISTS select name as "Customers" from customers cus where not exists (select 1 from orders ord where cus.id = ord.customerId)

[@pritishpattnaik4674]

ya got it , I was missing that AS part so getting wrong answer

[@sandeepmanjunath8004]

select name as customer from customers as c where not exists (select customer_id from orders as o where o.customer_id = c.id) ;

[@balaji27venkatesh]

-- efficient code select c.name as "Customers" from Customers as c left join Orders as o on c.id = o.customerId where o.id is null ---- simple to understand but not efficient code select name as "Customers" from Customers where id not in (select distinct Customerid from Orders)

[@frederikmuller]

I see you’re solving a lot of questions on this channel, keep it up.

[@xt8382]

Thanks!

[@mohit4812]

best