[ENHANCEMENT]: Implementation of distinct

[Kyryus]

Feature Description

Hello I am not sure it is really possible as I think "distinct" is not existing in all SQL language but do you plan to implement it ?

I see that in your example you use it with RAW queries only.

Thank you for your feedback

[lroal]

I think the aggregate function (groupBy) will work the same as DISTINCT.
In the example below, it will do a groupBy on customerId and customerName. If you remove the numberOfLines and totals, you have DISTINCT.

import map from './map';
const db = map.sqlite('demo.db');

getAggregates();

async function getAggregates() {
  const orders = await db.order.aggregate({
    where: x => x.orderDate.greaterThan(new Date(2022, 0, 11, 9, 24, 47)),
    customerId: x => x.customerId,
    customerName: x => x.customer.name,
    numberOfLines: x => x.count(x => x.lines.id),
    totals: x => x.sum(x => lines.amount)    
  });
}

[lroal]

Will it work for you ?
I should write a note in the documentation about DISTINCT.

[Kyryus]

Hello Iroal, thank you for the fast answer.

I know that the GROUP is the same but I read somewhere that for huge quantity of data GROUP BY is less efficient. However for little quantity of data, there is no difference of performance.

Anyway I think that using RAW query for this specific case is not absurd.

[lroal]

I can always add distinct. Much of it will just be copy paste from the aggregate function.