Questions tagged [union]

Please utilize this specific tag solely for inquiries related to UNION, which is a SQL keyword used to merge the outcomes of various SQL queries. For questions related to the UNION-ALL keyword, please use the [union-all] tag. If your inquiry pertains to unions in languages such as C, C++, and others alike, kindly use the [unions] tag instead.

Is there a deeper philosophical rationale behind choosing to use (or not use) enums in TypeScript, along with string union types?

Recently, I delved into the world of enum and const enum in Typescript, causing some confusion. I grasped that const enum gets transpiled into simple values while regular enums do not. I also recognized certain distinctions between using string union type ...

What is the reason that a combination of two types in a list does not result in a list of combinations of these two types?

I encountered some difficulties with using mypy in scenarios where List and Union types are combined. Although I have found the solution, I wanted to share my discoveries here. The core question that arose was: why does a list of a union of two types not ...

Combining arrays of Mongoose ObjectIds with Lodash union

I've encountered an issue with 2 arrays that contain ObjectId items: array1 and array2. My goal is to generate a union of the two arrays. To achieve this, I utilized the following code: let res = _.union(array1, array2); However, the resulting res ...

Spread an all-encompassing category across a collection

What is the method in TypeScript to "spread" a generic type across a union? type Box<T> = { content: T }; type Boxes<string | number> = Box<string> | Box<number>; (Given that we are aware of when to use Boxes versus Box) ...

Retrieve information from one table and compare it with another table to display any matches

Here's the scenario. I have successfully implemented joins in various parts of the website, but there's one issue that has been causing me quite a headache. It's likely something simple that I'm overlooking. This system allows users to log in and follow e ...