You can't dynamically set parameter vals.
Why can't your SQL use the values directly as fetched? Why add the step to use a parameter? Maybe you need to. I'm just curious.
This can be done one of two ways.
URL Click actions to a receiving dashboard passed as URL parameters.
Or through a custom web portal that passes the values in as URL parameters to src of the iframe.
If you comfortable doing either of these two approaches I can describe the one you prefer in more detail.
Thanks Aaron and Joe-
After Joe's reply I was thinking about trying to pass it in a URL parameter. It sounds a bit tricky to me to pass two date parameters in a URL string. If you have any examples of the date format, this would be helpful. I do know how to setup the actions to pass parameters in a URL string.
I agree with Joe Oppelt. Are INCIDENT_NUMBERs unique within your data source? If they are, couldn't you just use attr([Start Date]) and attr([Resolved Date]) as the parameters passed to the dynamic sql query. (Confession: I've never used dynamic sql queries in Tableau, so I may be making some inappropriate assumptions here.) If you do need to use the parameters, I would lean towards the URL click action approach that Aaron Clancy has suggested.
At Zac, you can't pass field values in to custom SQL. Only explicitly defined parameters.
I was going to say I agree with building the values in to the query directly (assuming the values are accessible in the same DB)
The reason why this might not be feasible is if the start and resolved dates are dynamic based off of some user interaction that gets those resulting values.
If this is not the case and the values are singular and pulled directly from a table then you could definitely just build this in to the query.
Let me know which assumptions are correct/incorrect.
I had a feeling there would be some limitation preventing you from using field values/calculations in a dynamic SQL pull.