How can I use Knex.js for aggregations in Node.js?

How can I use Knex.js for aggregations in Node.js?

You can use Knex.js to perform aggregations by utilizing its query builder methods like count, sum, avg, etc. For example, to get the total number of users, you can write: knex('users').count('* as total').

Can you show me an example of summing a column?

Sure! To sum a column, you can use the sum method. For instance: knex('orders').sum('amount as totalAmount') will give you the total amount from the 'orders' table.

What if I want to group the results?

You can use the groupBy method along with your aggregation. For example: knex('sales').select('category').sum('amount').groupBy('category') will group the sales by category and sum the amounts.

Is there a way to filter the results before aggregating?

Yes, you can chain the where method before your aggregation. For example: knex('sales').where('status', 'completed').sum('amount') will sum only the completed sales.