DAX Function to Retrieve Data from a Table

In DAX, there isn't a direct equivalent to SQL's SELECT * because DAX operates in a more context-aware fashion within data models. However, you can create a calculated table to return all columns from a specified table. Below is a structured DAX function that achieves this.

Function Definition

Purpose

To create a calculated table that retrieves all rows and columns from the est.estid table.

Parameters

• None

Return Type

• A table containing all records and columns from the est.estid table.

Example

GetEstData = 
    -- Create a new calculated table called GetEstData
    ADDCOLUMNS(
        -- Retrieve all rows from the est.estid table
        est[estid],
        "AdditionalColumn", 
        // Add any additional logic here if required
        1
    )

Steps and Explanation

1. Table Reference: The function references the table est[estid]. Ensure that this is the correct table name as per your data model.

2. ADDCOLUMNS Usage: Here, we are using the ADDCOLUMNS function to construct a new table. This directly extracts all the columns from est.estid.

3. Additional Logic Placeholder: In this example, a placeholder column "AdditionalColumn" is added just for demonstration. You can modify or remove this as needed.

Input Validation

As DAX operates in a data model, explicit input validation isn't typically required as seen in programming languages like Python or Java. However, ensure:

• The table est.estid exists in your data model.
• The data types of columns in est.estid are appropriate for the intended analysis.

Usage Example

To utilize this function in Power BI:

• Go to "Modeling" in Power BI.
• Click on "New table".
• Enter the formula provided above.

This will create a new table in your data model called GetEstData, containing all entries from the est.estid table.

Best Practices

• Ensure your data model is optimized, as large datasets can impact performance while using calculated tables.
• Regularly validate data integrity post-creation of calculated tables to confirm there are no discrepancies.

Additional Resources

For further learning and expertise enhancement in DAX, consider exploring courses available through the Enterprise DNA Platform.