Hi , you can still merge tables in Power BI when using DirectQuery mode. However, the process is a bit different than when using Import mode.
When using DirectQuery mode, merging of tables is done through relationships between the tables in your data source.
Create a relationship between tables in DirectQuery mode:
In the Manage Relationships dialog box, click the "New" button.
Select the first table you want to relate to another table from the dropdown list.
Select the column in the first table that you want to use as the relationship key.
Select the second table that you want to relate to the first table.
Select the column in the second table that you want to use as the relationship key.
Click "OK" to save the relationship.
Keep in mind that when using DirectQuery mode, some features in Power BI, such as certain types of calculations and transformations, may not be available or may be limited. Additionally, the performance of your report may be impacted by the size and complexity of your data source.