DAX Function to Identify Missing OfficialStationNames

Overview

This DAX function is designed to compare the OfficialStationName column from the tblFacilityVisnRelation table with the OfficialStationName column in the bi vLastUpdate_RSG table. The goal is to identify any official station names that are present in tblFacilityVisnRelation but missing in the bi vLastUpdate_RSG.

Function Definition

The following DAX code snippet defines a calculated table that will return a list of missing OfficialStationNames:

MissingOfficialStationNames = 
VAR FacilityNames = SELECTCOLUMNS(tblFacilityVisnRelation, "OfficialStationName", tblFacilityVisnRelation[OfficialStationName])
VAR UpdatedNames = SELECTCOLUMNS('bi vLastUpdate_RSG', "OfficialStationName", 'bi vLastUpdate_RSG'[OfficialStationName])
RETURN 
    EXCEPT(FacilityNames, UpdatedNames)

Explanation

1. Variable Definitions:

   • FacilityNames: This variable extracts the OfficialStationName column from the tblFacilityVisnRelation table using SELECTCOLUMNS.
   • UpdatedNames: This variable retrieves the OfficialStationName column from the bi vLastUpdate_RSG table.

2. Identifying Missing Names:

   • The EXCEPT function returns the list of OfficialStationNames that exist in the FacilityNames variable but do not exist in the UpdatedNames variable.

Input Validation

While DAX does not support traditional input validation like other programming languages, it's essential to ensure that:

• The columns being referred to in the tables are correctly named and exist in the respective tables.
• Both tables (tblFacilityVisnRelation and bi vLastUpdate_RSG) are loaded into the model.

Code Usage Example

Suppose you have two tables:

• tblFacilityVisnRelation with OfficialStationName values like "Station A", "Station B", "Station C".
• bi vLastUpdate_RSG with OfficialStationName values like "Station A", "Station C".

When you run the above DAX code:

• The result will be a new calculated table MissingOfficialStationNames that displays "Station B" since it is the only official station name that is missing from bi vLastUpdate_RSG.

Conclusion

This DAX function efficiently identifies missing OfficialStationNames across two tables, highlighting discrepancies in official station data. For hands-on experience and deeper insights into advanced DAX functions and data modeling techniques, consider exploring courses offered on the Enterprise DNA platform. This will augment your analytics skills and enhance your understanding of DAX functionalities.