Merge multiple tables into one table visual

Hi!

Yes you need to model your data for that. In this case you need to create relationsships between the three tables on the "Category" column (as you mentioned).

I would recommend you to follow this MS learning path to learn the basics:

https://learn.microsoft.com/en-us/training/paths/model-data-power-bi/ 

As table 2 and 3 seem to have the same content (category and date) it would be helpful to merge them together first. This way you have a simple model with only two tables and one relationsship:

Just experiment around a bit and get a clear understanding what information each of the tables is supposed to represent in your model. Hint: The "Item" column seems a bit out of place, as here it can only work as some kind of text explanation for your categories.

One word of caution:

You have to make sure that the values in the categories in your base table are unique, i.e. only appear once.

The reason for this is that you want to create a 1:n relationsship to the other table (A category value only appears once TO category value can appear more than once in the other table).