Please take a look at this part of the manual:
https://docs.inductiveautomation.com/display/DOC80/Basic+SQL+Query
There’s some datetime/string manipulation if you want to use that default Start/EndDate parameters with Basic SQL Query.
Another alternative as advised by Ignition trainer is as follows:
“Rather than converting your StartDate and EndDate report parameters to strings, you can use a query type of “SQL Query”, then use “?” characters in your query to inject parameters. This will gracefully handle dates passed in from the Report Viewer component.”