Variables in datasets: what's their use?

[luis_abreu]

Hello guys.

I'm taking a look at how to create custom datasets and I'm trying to understand what's the purpose of the variable section. Initially, I thought it could be used for filtering data, but it seems like I don't need them to filter data in the report (it seems like I can use any of the fields on the table that is being passed through the dataset to filter data).

Can anyone please explain me how they're supposed to be used?

Thanks.

[luis_abreu]

Hello again. If I'm wrong, please correct me. From my tests, it seems like variables are useful for those scenarios where you need to have an expression that needs to be applied to a column before applying it on a filter (ie, instead of comparing directly with the value of a column). BTW, anyone knows how to get the complete sql that is executed against the db? If there's an error on the filter expression, I've noticed that we get part of the sql on the report diagnostics. However, when everything works without any errors, there's no feedback on the sql that gets executed. Thanks.