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## Resource: wix-data

## Namespace: wix-data-distinct

## Article: Introduction

## Article Link: https://dev.wix.com/docs/velo/apis/wix-data/wix-data-distinct/introduction.md

## Article Content:

# Introduction
The `WixDataDistinct` methods allow you to refine a distinct query before it runs, as well as sort and limit its results. A distinct query returns unique values for the specified property, without duplicates.

To refine the distinct query, use `WixDataDistinct` methods in the [`beforeDistinct()`](https://dev.wix.com/docs/velo/events-service-plugins/data/hooks/wix-data-hooks/before-distinct.md) hook. This hook is triggered when you call [`distinct()`](https://dev.wix.com/docs/velo/api-reference/wix-data/wix-data-query/distinct.md), and runs before the distinct query operation executes.

For example, the following hook refines the distinct query by adding an age requirement, and then sorts the results in ascending order:


 ```javascript
// In site backend code

import wixData from "wix-data";

wixData
  .query("customers")
  .distinct("lastName") // Triggers the beforeDistinct() hook
  .then((results) => {
    if (results.items.length > 0) {
      let items = results.items;
    } else {
      // handle case where no matching items found
    }
  })
  .catch((error) => {
    let errorMsg = error.message;
    let code = error.code;
  });


// In data.js

export function myCollection_beforeDistinct(distinct, context) {
 // Get the current filter
 const currentFilter = distinct.getFilter();

 // Add an age requirement
 const updatedFilter = currentFilter.ge("age", 18);

 // Set the updated filter and sort the results
 const updatedDistinctQuery = distinct.filter(updatedFilter)
   .ascending();

 return updatedDistinctQuery;
}
 ```

 You can further refine the distinct query by chaining additional `WixDataDistinct` methods.