How to use Bases in Obsidian

Understanding Obsidian's Filter Logic: A Guide to Nested Conditions

Introduction

• Obsidian's database views offer powerful filtering, but the nested logic can be confusing
• Understanding AND vs OR logic is crucial for getting the results you want
• This guide will help you visualize how filters combine

Core Concepts

The Two Building Blocks

1. "Any of the following are true" (OR logic)

   • Item matches if it satisfies AT LEAST ONE condition
   • Think: "this OR that OR the other thing"

2. "All of the following are true" (AND logic)

   • Item matches ONLY if it satisfies EVERY condition
   • Think: "this AND that AND the other thing"

How Nesting Works

• Filters can be nested inside other filters
• Each filter group treats its children as a list of options
• Understanding the hierarchy is key

Common Mistakes

Mistake #1: Thinking Nested Groups Apply to Everything Above

What people expect:

Show me items where:
- fileClass is article OR software OR prompt
- AND description is empty

What they actually create:

Show me items where ANY of these are true:
- fileClass is article
- fileClass is software
- fileClass is prompt
- description is empty

The problem: The "description is empty" becomes just another OR option, not a requirement

Mistake #2: Mixing Up Group Types

• Using "Any" when you need "All"
• Not realizing which group your condition is inside

How to Think About Filter Structure

Visual Method: The Indentation Tree

• Each indent level represents nesting
• Conditions at the same indent level are siblings
• Look at what connects them: "or" or the group label

Sentence Method: Read It Aloud

Convert your filter to plain English:

• "Show items where ANY of (A or B or C or D)"
• vs "Show items where ALL of (ANY of (A or B or C) AND D)"

Diagram Method: Using Venn Diagrams

• OR = union of circles (anything in either circle)
• AND = intersection (only the overlap)

Building Filters Step by Step

Example 1: Items with specific fileClass AND empty description

Goal: Find articles, software, or prompts that don't have descriptions yet

Wrong way:

Any of the following:
  - fileClass is article
  - fileClass is software
  - fileClass is prompt
  - description is empty  L (This makes it OR!)

Right way:

All of the following:
  - Any of the following:
      - fileClass is article
      - fileClass is software
      - fileClass is prompt
  - description is empty  

Example 2: Complex filters with multiple requirements

Goal: Show urgent tasks that are either unassigned OR assigned to me

All of the following:
  - priority is high
  - Any of the following:
      - assignee is empty
      - assignee is [your name]

Example 3: Excluding items

Goal: Show all articles except drafts with no date

All of the following:
  - fileClass is article
  - Any of the following:
      - status is not draft
      - date is not empty

Troubleshooting Your Filters

When results don't match expectations:

1. Write out what you want in plain English

   • "I want items that are X AND have Y"
   • "I want items that are X OR Y but NOT Z"

2. Identify the main connector

   • Is your goal AND (all conditions must be true)?
   • Or is your goal OR (any condition can be true)?
   • That determines your outer group type

3. Build from the outside in

   • Start with your main group type (All/Any)
   • Add nested groups for complex sub-conditions
   • Test after each addition

4. Check the indentation

   • Are conditions at the same level siblings?
   • Is your condition inside the right parent group?

Practical Exercise

Try building these filters yourself:

Exercise 1: Find all books or articles published in 2024 or 2025

All of the following:
  - Any of the following:
      - fileClass is book
      - fileClass is article
  - Any of the following:
      - year is 2024
      - year is 2025

Exercise 2: Find incomplete tasks that are high priority AND (due today OR overdue)

All of the following:
  - status is not complete
  - priority is high
  - Any of the following:
      - dueDate is today
      - dueDate is before today

Quick Reference Card

Conclusion

• Filter logic follows boolean algebra (AND/OR)
• Nesting creates hierarchy - understand your structure
• When confused, write it out in plain English first
• Test incrementally to catch mistakes early

For the video version:

• Screen recording showing the exact issue from your screenshots
• Live demonstration building filters step by step
• Side-by-side comparison of wrong vs right filter structure
• Real-time testing showing how results change
• Annotated diagrams overlaid on screen
• Common pitfalls section with examples from real use cases