What does the Qualify function do for field names?

The Qualify function is used to rename field names in a specific format to ensure that they are unique within the context of the data model. This is particularly useful in scenarios where multiple tables might contain the same field name, as it helps prevent ambiguities during data loading and analysis. By qualifying the fields, you can maintain clarity and avoid potential conflicts that could arise from having identical field names across different tables.

When the Qualify function is applied, it typically prefixes the field names with the name of the table they originate from, following a convention that allows for easy identification. This structured approach not only enhances the organization of the data model but also aids in troubleshooting and maintaining the model over time as it grows more complex.

The other options do not accurately describe the function or purpose of the Qualify function in Qlik Sense. For instance, while changing case, extracting substrings, or repeating strings can be handled by other functions in Qlik Sense, they do not pertain to the function of naming fields in the context of creating a well-organized data model.