---
title: Field Mapping
slug: segment/field-mapping
docTags: 
createdAt: 2026-01-15T19:51:24.746Z
---

By field mapping you define which fields from your Selected Data Extensions will populate the fields of your Target Data Extension. You can configure this data transfer manually by dragging and dropping specific fields or let Unaric Segment match them automatically.

Automap matches the fields from the Available Fields with the fields in the Target Data Extension based on names and field types.

There are two scenarios where Automap will not work: 

- **The field type is not compatible**. For example, an Email field *isActive* will not match to a Boolean field with the same name.
- **There are multiple fields under Available Fields with the same name**. For example, if you have joined *Accounts* and *Contacts* Data Extensions and both have an *Id* field, Automap will not map to an *Id* field in your Target Data Extension.

:::hint{type="success"}
We recommend using Automap to get the majority of your fields mapped and then map the remaining ones manually.
:::

### (Do Not) Overwrite

Automap has 2 options: **Overwrite** / **Do Not Overwrite**

- **Overwrite: **Any existing mappings will be overwritten by the mappings defined by the Automap functionality.
- **Do Not Overwrite:** Automap will try to map fields that were not mapped yet, but will respect any existing mappings.

## Map source data to Target Data Extension

Assuming you prepared a Data Extension in advance to save your Selection, you can follow the following steps on the** Output** step:

1. Select if you want to create a new Data Extension or select an existing one.
2. After choosing your Data Extension, you will see that all its fields will appear on the right side of the screen, and your source Data Extensions/Data Views will appear on the left-hand side under the **Available Fields **section.
3. You can now map the fields (choose how to populate each target field with any of the source fields) manually by drag-and-dropping the correct fields to the right.

## Delete mappings

At any time you can delete existing mappings by clicking the delete icon next to the name of a field in the mapping table. Alternatively, all current mappings can be deleted by clicking the **trash bin** button inside the **Tools** option in the upper right corner. This can be useful when you want to switch one of the source Data Extensions.

:::hint{type="warning"}
When you switch to another Target Data Extension, all existing mappings will be lost.
:::

## Field Type compatibly for mapping

Select which fields from your Selected Data Extensions will populate the fields of your Target Data Extension by creating mappings. 

Unaric Segment is responsible for translating your selections to SQL. In SQL not all field type conversions are allowed. To prevent you from using invalid conversions, Unaric Segment does not allow all mappings depending on the field types you are trying to map.

In the table below you can see all the filed type mappings that Unaric Segment does **not** consider compatible:

| **Selected Data Extension / Custom Value field** | **Target Data Extension field** |
| ------------------------------------------------ | ------------------------------- |
| **TO**                                           |                                 |
| TEXT                                             | DATE                            |
| TEXT                                             | BOOLEAN                         |
| DATE                                             | TEXT                            |
| BOOLEAN<br />****                                | TEXT                            |

:::hint{type="success"}
Use proper field types. For example, define a text field as a Text data type or a number field using the Number data type. Do not store numbers as text unless you plan to combine or join them with Data Views since they are usually stored as Text data type in SFMC.
:::