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

# Advanced UQL: Cross-Object Queries & Analysis

> An advanced guide for architects and power users on writing complex UQL queries, including traversing object relationships, using functions, and performing historical analysis.

## Beyond the Basics

You've mastered the basic `field = "value"` structure of UQL. Now it's time to unlock its true power: the ability to ask deep, relational questions that span across your entire business data model.

This guide covers advanced patterns that will allow you to perform sophisticated data analysis, focusing on **cross-object queries**, **built-in functions**, and **historical queries**.

## The Core of Advanced UQL: Cross-Object Queries

This is the most powerful feature of UQL. When you have an `Object Picker` field or a `Parent-Child` relationship, UQL allows you to "walk" across that relationship using **dot notation** to query fields on the referenced `🧊 Object`.

#### The 'Dot Notation' Syntax

The syntax is simple and intuitive: `referencing_field_key.field_on_referenced_object`

* **Simple Example:** Find all `Projects` for enterprise clients.
  * Your `🧊 Project` Object Type has an `Object Picker` field with the key `client`.
  * **UQL Query:** `client.tier = "Enterprise"`
  * **Explanation:** `client` is the field on the `🧊 Project`, and `tier` is a field on the referenced `🧊 Client` Object.
* **Multi-Level Example:** Find all `Tasks` where the parent `Project`'s `Client` is based in "New York".
  * **UQL Query:** `parent.client.city = "New York"`
  * **Explanation:** You can chain together multiple references to traverse complex relationships in your data model (`Task` → `Project` → `Client`).

\[Image Placeholder: A diagram showing three linked Object Types (Task -> Project -> Client) with their fields. A UQL query box below shows the `parent.client.city` query, with arrows pointing from each part of the query to the corresponding field in the diagram.]

## Using Functions in UQL

UQL includes built-in functions to handle dynamic values and more complex logic.

| Function           | Description                                                                            | Example                      |
| :----------------- | :------------------------------------------------------------------------------------- | :--------------------------- |
| `currentUser()`    | A dynamic value representing the user currently running the query.                     | `assignee = "currentUser()"` |
| `now()`            | The current date and time.                                                             | `start_date > "now()"`       |
| `today()`          | The current date (without time).                                                       | `due_date = "today()"`       |
| `count(field_key)` | Counts the number of items in a multi-value field (e.g., a `Multiple Objects Picker`). | `count(sub_tasks) > 10`      |

## Querying History

As covered in our guide to [Leveraging Workflow Data](/platform/core-concepts/workflow-and-status/using-workflow-data), you can use special operators to query the history of an `🧊 Object`'s status changes. This is a powerful feature for process analysis.

* **Example:** `status changed from "IN_REVIEW" to "APPROVED"`
* **Use Case:** This is essential for building `Dashboards` that measure process efficiency or `Saved Filters` that find `🧊 Objects` that have ever passed through a critical review stage.

## Putting It All Together: A Complex Example

By combining these advanced techniques, you can answer very specific business questions.

* **Business Question:** "Find all `IN_PROGRESS` `Tasks` assigned to me, which belong to a `Project` for an 'Enterprise' tier `Client`, and where that `Project` has more than 5 stakeholders."
* **UQL Query:**

  ```uql theme={null}
  status = "IN_PROGRESS" AND assignee = "currentUser()" AND parent.client.tier = "Enterprise" AND count(parent.stakeholders) > 5

  ```

\[Guidejar Placeholder: A tutorial showing a power user in the 'Saved Filter' UQL editor. They build the complex query above step-by-step, and the live preview on the right updates to show the filtered results.]

## What's Next?

Congratulations! You have now completed the deep dive into all of the Core LEGO Pieces of the Luklak platform, from the `Universal Object` to the `UQL` engine that queries them.

You have the full architectural knowledge. It's time to put it all together and build your first complete solution.

* [**Go to the Build Playbooks**](/en/03-build/introduction)
* [**Return to the Platform Overview**](/en/02-platform/platform-overview)