10. Qualify and UnQualify in Qlik Sense

Introduction

This tutorial explains how to use the Qualify and UnQualify functions in Qlik Sense. These functions help manage field names, especially when working with multiple data sources. Understanding how to qualify and unqualify fields is essential for maintaining data integrity and avoiding confusion in your visualizations.

Step 1: Understanding Qualify

Qualifying a field in Qlik Sense means that the field name will be prefixed with the table name, helping to distinguish between fields with the same name from different tables.

How to Qualify a Field

• Use the QUALIFY statement in your script.
• Example:

  QUALIFY FieldName;
  

• This will change FieldName to TableName_FieldName if it exists in TableName.

Practical Tips

• Always qualify fields when combining data from different sources to prevent naming conflicts.
• Use QUALIFY *; to qualify all fields in a table.

Step 2: Implementing UnQualify

To revert a field back to its original name, you will use the UnQualify function. This is useful when you want to remove the prefix added by the Qualify function.

How to UnQualify a Field

• Use the UNQUALIFY statement in your script.
• Example:

  UNQUALIFY FieldName;
  

• This will remove the prefix from TableName_FieldName, returning it to FieldName.

Practical Tips

• Use UNQUALIFY *; to unqualify all fields from a specific table.
• Be cautious when using UnQualify, as it may lead to conflicts if multiple tables have fields with the same name.

Step 3: Combining Qualify and UnQualify

You can mix both functions in your script to manage field names effectively.

Example Scenario

• Start with qualifying fields to avoid conflicts.
• Later in your script, unqualify specific fields as needed for clarity in your final data model.

Example Code

QUALIFY FieldName1, FieldName2;
UNQUALIFY FieldName1;

Conclusion

In this tutorial, you learned how to use the Qualify and UnQualify functions in Qlik Sense to manage field names effectively. By qualifying fields, you prevent naming conflicts, while unqualifying helps maintain clarity when needed. Next steps include practicing these functions in your Qlik Sense scripts to see their impact on your data models.