--- title: "Dax@2" description: "Dax@2 — Power BI, MS Fabric and Azure Analysis Services semantic models and SSAS tabular and multidimensional models, queried in DAX or MDX, no driver needed" url: "https://docs.justcat.it/reference/data-sources/providers/dax-2/" --- # Dax@2 ## Connects to Semantic models in Power BI and Microsoft Fabric workspaces, semantic models in Azure Analysis Services, and tabular and multidimensional models in SQL Server Analysis Services (SSAS): Power BI Semantic Model, MS Fabric Semantic Model, Azure Analysis Services, SQL Server Analysis Services. It is technically possible to query a locally open Power BI Desktop file through `Dax@2`, but [PowerBI@2](https://docs.justcat.it/reference/data-sources/providers/powerbi-2/ "PowerBI@2") is much more convenient for that case. ## Example **Properties** Name : My Power BI Dataset Provider : Dax@2 Technology : PowerBISemanticModel Connection string : ``` Data Source=powerbi://api.powerbi.com/v1.0/your-organization.com/your-workspace-name; Initial Catalog=Your-Dataset-Name; User ID=%YOUR_SERVICE_PRINCIPAL_NAME_ENVIRONMENT_VARIABLE_NAME%; Password=%YOUR_SERVICE_PRINCIPAL_SECRET_ENVIRONMENT_VARIABLE_NAME%; ``` **YAML** ```yaml Data sources: - Name: My Power BI Dataset Provider: Dax@2 Technology: PowerBISemanticModel Connection string: > Data Source=powerbi://api.powerbi.com/v1.0/your-organization.com/your-workspace-name; Initial Catalog=Your-Dataset-Name; User ID=%YOUR_SERVICE_PRINCIPAL_NAME_ENVIRONMENT_VARIABLE_NAME%; Password=%YOUR_SERVICE_PRINCIPAL_SECRET_ENVIRONMENT_VARIABLE_NAME%; ``` Replace the placeholders (your-organization.com, your-workspace-name and your-dataset-name) with real values. ## Connection string An Analysis Services (ADOMD.NET) connection string — `Key=Value` pairs separated by semicolons. The keys you will use most: | Key | Meaning | |---|---| | `Data Source` | For a Power BI or MS Fabric workspace its XMLA endpoint, `powerbi://api.powerbi.com/v1.0//`; for Azure Analysis Services the `asazure://…` address; for SSAS the server name | | `Initial Catalog`, `Catalog` | The semantic model (dataset, database) to query | | `User ID`, `Password` | Service principal name and secret | | `Integrated Security` | `SSPI` for a local SSAS instance | The full list is in the Analysis Services connection string reference. A password, or the whole string, can come from an environment variable — `%NAME%` is replaced with the value of `NAME`; see [How every provider is used](https://docs.justcat.it/reference/data-sources/providers/introduction/#how-every-provider-is-used "How every provider is used"). **Workspaces.** A Power BI or MS Fabric workspace is reached through its XMLA endpoint, which needs Power BI Premium, Premium per user or a Fabric capacity. The example above signs in as a service principal that has a secret and access to the workspace. Without a service principal you can still automate your tests, but expect the standard Microsoft login prompt — leave both credentials empty: **Properties** Name : My Power BI Dataset Provider : Dax@2 Technology : PowerBISemanticModel Connection string : ``` Data Source=powerbi://api.powerbi.com/v1.0/your-organization.com/your-workspace-name; Initial Catalog=Your-Dataset-Name; User ID=; Password=; ``` **YAML** ```yaml Data sources: - Name: My Power BI Dataset Provider: Dax@2 Technology: PowerBISemanticModel Connection string: > Data Source=powerbi://api.powerbi.com/v1.0/your-organization.com/your-workspace-name; Initial Catalog=Your-Dataset-Name; User ID=; Password=; ``` Both ways of testing Power BI data — on your machine and in a workspace — are walked through in [Test Power BI](https://docs.justcat.it/how-to-guides/data-platforms/power-bi/test-power-bi/ "Test Power BI"). **SSAS.** A local or on-premises instance, with integrated security: **Properties** Name : My Tabular Model Provider : Dax@2 Technology : Ssas Connection string : ``` Provider=MSOLAP; data source=localhost; integrated security=SSPI; Catalog=WideWorldImporters; ``` **YAML** ```yaml Data sources: - Name: My Tabular Model Provider: Dax@2 Technology: Ssas Connection string: > Provider=MSOLAP; data source=localhost; integrated security=SSPI; Catalog=WideWorldImporters; ``` The `Provider=MSOLAP;` part is accepted and not needed — the driver is ADOMD.NET. ## Settings None beyond `Connection string`. ## Query Tabular and semantic models do not understand SQL. The statement is one DAX query — **knowledge of at least the very basics of DAX is required**; multidimensional models in SSAS take MDX instead. [GUI for DAX queries](https://docs.justcat.it/how-to-guides/data-platforms/power-bi/get-the-dax-query-behind-a-visual/ "GUI for DAX queries") shows how to build a query without prior DAX knowledge. A test comparing the data a DAX query returns (a made-up example without much sense) with expected data provided in YAML: ```yaml Tests: - Name: Check zip codes First Data Source: MyTabularModel First Query: | EVALUATE( TOPN(3,VALUES('Customer'[Postal Code])) ) ORDER BY 'Customer'[Postal Code] Second data source: yaml Second Query: /Expected results Expectation: sets match ``` ## Prerequisites None. The driver ships with CAT; Windows and Linux alike. ## Limitations * Cannot serve lists of definitions — DAX returns column names in square brackets (`Tests[Test name]`, `[Test name]`), which CAT does not match to property names. ## Serving test and data source definitions `Dax@2` cannot serve [lists](https://docs.justcat.it/reference/project-file/lists/ "Lists") of definitions. A DAX query returns its column names in square brackets — `Tests[Test name]` for a model column, `[Test name]` for a column the query names itself — and CAT matches definition properties by name, brackets included: `[Test name]` is not `Test name`. ## Related * [Technologies](https://docs.justcat.it/reference/data-sources/technologies/ "Technologies") — the semantic and tabular model platforms this provider serves. * [Test Power BI](https://docs.justcat.it/how-to-guides/data-platforms/power-bi/test-power-bi/ "Test Power BI") — testing a local file and a workspace model, step by step. * [GUI for DAX queries](https://docs.justcat.it/how-to-guides/data-platforms/power-bi/get-the-dax-query-behind-a-visual/ "GUI for DAX queries") and [DAX introduction](https://docs.justcat.it/how-to-guides/data-platforms/power-bi/sql-to-dax/ "DAX introduction") — getting started with DAX.