> ## Documentation Index
> Fetch the complete documentation index at: https://docs.usedatabrain.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Dashboard Filter - Variable Apply On

> In this page you can see the functioning of variable apply on method available in Dashboard Filters.

Using Variable Filter in Dashboard Filter with Custom SQL

### Creating a Dashboard Filter with Variable Filter:

1. Create Dashboard Filter
2. In the “Apply On” section, choose **"Variable Filter"**
3. Assign Variable Name:
   * Assign a variable name, for example, `{{global_value}}` for Dashboard Filter.
   * Copy the variable `{{global_value}}` for use in your custom SQL query.

<Frame alt="Dashboard filter showing variable filter apply-on selection">
  <img src="https://mintcdn.com/databrainlabs-bef6850a/KRwjKFDucjw_bmHb/images/guides/variable-filter.png?fit=max&auto=format&n=KRwjKFDucjw_bmHb&q=85&s=20c827cbf37b8ced1f813e5d20662458" width="1534" height="1184" data-path="images/guides/variable-filter.png" />
</Frame>

### Example Use Case: Dynamic Country Population Analysis

Let's say you're building a dashboard where analysts need to quickly filter population data for different countries without modifying the underlying SQL query each time. Here's how the Dashboard Filter would be valuable:

**Purpose:**

* Allows users to dynamically select different countries to view their population data
* Eliminates the need to write separate queries for each country
* Provides a user-friendly interface for non-technical users

**Example Custom SQL Query with Variable Filter:**

* **Custom SQL you write:**

<Frame alt="Example showing custom SQL query before adding variable filter">
  <img src="https://mintcdn.com/databrainlabs-bef6850a/jzYViQJeLwpwFJzr/images/guides/custom-sql-you-write.png?fit=max&auto=format&n=jzYViQJeLwpwFJzr&q=85&s=ac4596cec7b69d8174c62e4a4b415a21" width="2940" height="1656" data-path="images/guides/custom-sql-you-write.png" />
</Frame>

* **Custom SQL added with Variable Filter:**

<Frame alt="Example showing SQL query updated with variable filter">
  <img src="https://mintcdn.com/databrainlabs-bef6850a/jzYViQJeLwpwFJzr/images/guides/custom-sql-with-variable-filter.png?fit=max&auto=format&n=jzYViQJeLwpwFJzr&q=85&s=01acc78f172acfb0bf9765d60625e82b" width="2940" height="1660" data-path="images/guides/custom-sql-with-variable-filter.png" />
</Frame>

Then the Generated SQL we generate would look like this:

* **Resulting SQL:**

<Frame alt="Generated resulting SQL after applying variable filter">
  <img src="https://mintcdn.com/databrainlabs-bef6850a/KRwjKFDucjw_bmHb/images/guides/resulting-sql.png?fit=max&auto=format&n=KRwjKFDucjw_bmHb&q=85&s=e5f67d2bac6a3eae40da5a648dbc2345" width="2940" height="1660" data-path="images/guides/resulting-sql.png" />
</Frame>

### Working:

* Initial SQL query gets all country population data
* Variable Filter adds a WHERE clause with `{{global_value}}`
* When users select a country from the filter, it automatically updates the query
* Results are instantly filtered to show only the selected country's data

### Important: Where and how to use the variable

* **Keep the variable in the WHERE clause** of your metric's SQL. The variable name must exactly match the filter's variable name (case-sensitive), and the filter needs a value or default — if the query runs while a `{{variable}}` is still unresolved, you get: **Error: Filter or Client variables detected in the query.** There is no built-in way to display or "inspect" the current filter value in a metric, so a variable in SELECT has no supported use.
* **Single-select filter:** The variable is replaced by a single quoted value; use `WHERE column = {{var}}`.
* **Multi-select filter:** The variable is replaced by a parenthesized list of quoted values, e.g. `( 'US' , 'CA' )`; use `WHERE column IN {{var}}` — **without** your own parentheses (`IN ({{var}})` double-wraps into invalid SQL), and do not use `= {{var}}` for multi-select.

### Dashboard Result After Applying Filter with Variable Value

The metrics are filtered according to the values selected in the dashboard filter

<Frame alt="Dashboard output after selecting variable value in dashboard filter">
  <img src="https://mintcdn.com/databrainlabs-bef6850a/jzYViQJeLwpwFJzr/images/guides/dashboard-result.png?fit=max&auto=format&n=jzYViQJeLwpwFJzr&q=85&s=65e631630c9fe960ff3cb89328533478" width="2938" height="1656" data-path="images/guides/dashboard-result.png" />
</Frame>

<Check>
  Variable Apply-On Filter configured successfully. The filter now passes the selected value into your SQL query dynamically.
</Check>