# Understanding ArcMap's Definition Queries 'arcmap definition query'

ArcGIS Pro offers several powerful tools for managing and manipulating geographic data within its mapping environment. One such tool is the definition queries feature found under the Feature Layer properties dialog box in ArcMap.

## What are Definition Queries?

Definition queries serve as a mechanism to control which features appear on an interactive map or chart based on specific criteria defined by you, the user. Essentially, these queries act like filters that allow only relevant data points to be displayed while concealing all others from view within your mapped space - making it easier navigate through large datasets with ease!

## Creating and Managing Definition Queries

To access definition query settings for a layer in ArcMap:

1. Select the desired feature layer by clicking on its name once in the Layers panel (also known as 'Contents' depending upon which version of ArcGIS you are using).

2. Right-click anywhere within this selected item's context menu options and choose Properties from its drop-down list.

3. In the Layer Properties dialog box that appears next, navigate down through several tabs until reaching 'Definition Query'.

## Adding New Queries

To create a new definition query:

1. Click on 'New' button located at bottom-right corner of this tabbed interface; an empty text field will appear asking for its name alongside two dropdown menus labeled as Expression Type and Field(s).

2. For Expression Type, choose either 'Simple' or 'SQL', depending upon how complex your filter logic needs to be.

3. In the subsequent dialog box that opens:

- Select one of three options under 'Logic' (AND, OR, NOT) based on whether you want all conditions met ('AND'), any condition satisfied ('OR') or its negation ('NOT').

4. Click 'OK' twice when finished setting up your new definition query.

## Modifying Existing Queries

To modify an existing query:

1. In the Layers panel, right-click anywhere within a selected layer's context menu and choose Properties again.

2. Within the resulting Layer Properties dialog box:

- Navigate down to 'Definition Query' tab

3. Hover over the relevant row(s) until they turn into small blue 'i' icons appear beside each query name when mouse hovers over them; click on one such icon once it's highlighted.

## Editing, Adding or Removing Clauses from an Existing Definition

Once inside a specific definition query:

1. You'll see its current expression in the middle text area.

2. To modify this expression:

- Double-click anywhere within that field to open up its editor window where you can edit individual clauses as needed

3. Alternatively, if you want add more complex logic without completely starting from scratch:

- Click on '...' button at top-right corner next to 'Add Clause' dropdown menu instead; then choose either 'And', 'Or' or 'Not' depending upon what logical operator is required before adding another condition using same process described above.

In conclusion, definition queries are a powerful tool in ArcMap for managing and manipulating geographic data. By understanding how to create, modify, and manage these queries, you can efficiently control which features appear on your maps or charts based on specific criteria defined by you. This will enable you to better navigate through large datasets with ease while only displaying relevant information at any given time.

Hope this article has been helpful in explaining what definition queries are and how they work within ArcMap! If there's anything else related that I haven't covered here, feel free to ask me via comments below - happy mapping everyone!

Arcmap definition query