How to write MDX or DMX stored procedures

Learn how to create and execute MDX (Multidimensional Expressions) and DMX (Data Mining Extensions) stored procedures in SQL Server to perform advanced data analysis and business intelligence operations.

Introduction to MDX and DMX

SQL Server provides rich support for data analysis through its support of MDX and DMX languages. MDX is primarily used for querying and manipulating data in multidimensional databases, typically OLAP cubes. On the other hand, DMX is used for managing and querying data mining models, making it essential for advanced analytics and predictive modeling.

In this post, we’ll explore how to write stored procedures that utilize these languages within SQL Server. A stored procedure allows you to automate your queries and can be used to encapsulate MDX or DMX scripts for reusable and efficient data analysis.

Creating a Basic MDX Stored Procedure

MDX queries are often used for complex reporting and aggregating data in OLAP cubes. Below is an example of how to create a simple MDX query stored procedure:

CREATE PROCEDURE GetSalesData
AS
BEGIN
    -- MDX query to fetch sales data from an OLAP cube
    WITH 
    MEMBER [Measures].[Total Sales] AS
        SUM([Sales].[Amount])
    SELECT
        {[Measures].[Total Sales]} ON COLUMNS,
        [Date].[Calendar].[Year].MEMBERS ON ROWS
    FROM [SalesCube]
END;
        

This stored procedure executes an MDX query that retrieves the total sales for each year from the "SalesCube" OLAP cube. The SUM function is used to aggregate the sales data, and the result is returned by the procedure.

Creating a Basic DMX Stored Procedure

DMX is used for querying and managing data mining models. Below is an example of creating a DMX query stored procedure that predicts sales based on historical data:

CREATE PROCEDURE PredictSales
AS
BEGIN
    -- DMX query to predict sales using a trained mining model
    DECLARE @Prediction FLOAT;
    
    -- Use the 'Predict' function to get sales predictions from the model
    EXEC sp_executesql 
        N'SELECT Predict([SalesModel], @InputData) AS PredictedSales',
        N'@InputData NVARCHAR(MAX)',
        @InputData = N'{"Month": "January", "Year": 2025}';

END;
        

This DMX query stored procedure utilizes the Predict function to generate sales predictions based on the trained model [SalesModel]. The input data for the prediction is passed as a parameter, and the predicted sales value is returned by the procedure.

Executing MDX and DMX Stored Procedures

Once you’ve created your stored procedures, you can execute them from SQL Server Management Studio (SSMS) or use SQL Server Integration Services (SSIS) for automated execution. To execute a stored procedure, simply use the following SQL command:

EXEC GetSalesData;
EXEC PredictSales;
        

In the case of MDX, you would execute the procedure from the Analysis Services database, and for DMX, you can execute it directly from SQL Server.

Best Practices

• Modularize Queries: Store procedures should encapsulate only one purpose (e.g., a single report or prediction). This helps in maintaining them over time.
• Parameterization: Always use parameters instead of hard-coding values within the MDX or DMX query to make your procedure reusable and secure.
• Optimize Performance: When using MDX, avoid complex calculations on large datasets. Always consider the performance impact of your queries.
• Documentation: Comment your stored procedures well, especially if they involve complex logic or calculations.

For more information on MDX and DMX, refer to the official SQL Server documentation or explore community forums for use cases and best practices.