# Custom SQL

## Overview

Custom SQL unlocks full querying power for advanced analyses that exceed the point‑and‑click builders—complex joins, bespoke metrics, detailed exports, or data validation.

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## Common Use Cases

* Top N events or users over a custom window
* DAU / MAU or retention calculations with window functions
* Joining profiles to events for LTV or cohort reports
* Exporting a CSV list (e.g. high‑value customers) for marketing

***

## Interface Walkthrough

| Element    | Description                                                |
| ---------- | ---------------------------------------------------------- |
| SQL Editor | Write multi‑line queries; autocomplete for tables/columns. |
| Run Query  | Execute and preview results instantly.                     |
| Save Query | Store as a reusable insight.                               |
| Variables  | Parameterise dates, IDs, event names for easy reuse.       |
| Changelog  | View and revert past edits.                                |

***

## Quick Example (Daily Session Duration)

```sql
SELECT 
    toDate(session_start_time) AS date,
    median(session_duration / 60) AS average_session_duration_minutes
FROM (
    SELECT 
        toDate(timestamp) as date,
        sessionId,
        min(timestamp) AS session_start_time,
        toUnixTimestamp(max(timestamp)) - toUnixTimestamp(min(timestamp)) AS session_duration
    FROM eventsTable
    WHERE timestamp >= dateAdd(day, -30, today())
    GROUP BY date, sessionId
    HAVING session_duration > 0
)
GROUP BY date
ORDER BY date
```

1. Paste into editor → Run Query.
2. Table shows days and median session duration.
3. Save as “Daily Session Duration”; add a variable for the day interval if you want quick toggles.


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# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://userflux.gitbook.io/userflux-docs/feature-guides/analytics/insights/custom-sql.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.