add rules for time format, casing, sql & Codegen

CONTRIBUTIN.md

@@ -58,6 +58,8 @@ Do **not** change the formatting of license texts (e.g.
 - We use the string `TODO` to mark bits of code that need improvement.
 - We use the string `DEBUG` to mark bits of code that are only for debugging
   (remove before next commit).
+- We use `YYYY-MM-DD hh:mm:ss` (in `UTC`) as date & time format.
+- We use `camelCase` where possible.
 - We add (if possible) the following header to files that contain a reasonable
   amount of self-written code or are essential to the project:
 
@@ -82,6 +84,16 @@ Do **not** change the formatting of license texts (e.g.
 
 ### File specific rules
 
+#### SQL (.sql)
+
+- We avoid using spaces and keywords (escape with `` ` `` if necessary).
+- We write keywords in queries as `ALL CAPS`.
+- We name databases in `ALL CAPS`
+- We name tables in `PascalCase`.
+- We name columns in `camelCase`.
+- We name foreign keys in this scheme: `FK_SourceTable_sourceColumn`.
+- We prefix booleans with `IS_`.
+
 #### Markdown (.md)
 
 - We add a single `h1` element per document (as a title of the document).
@@ -99,7 +111,7 @@ Do **not** change the formatting of license texts (e.g.
   ---
   ```
 
-#### YAML
+#### YAML (.yaml)
 
 We indent using spaces (1 space wide).
 
@@ -119,6 +131,17 @@ We use the `.yaml` file ending.
 
 - We use `.graphqls` for defining our graph scheme.
 
+## Generating code/using tools
+
+This paragraph does not refer to code generation using neural networks/Ai/LLMs,
+which is currently disallowed, but instead to _classical Codegen_ (e.g.
+[gqlgen](https://github.com/99designs/gqlgen)).
+
+- We document the general steps & commands we use to generate code in
+  [CMD_HISTORY.md](./CMD_HISTORY.md) and commit the result without much
+  modifications. Instead, we commit the necessary changes in an additional
+  commit.
+
 ## Commit messages
 
 - We write in all lowercase except for special names, e.g. `update Makefile`