When writing HANA SQL you sometimes need access to more advanced features in the SQL script.
To enable the features you will need to wrap your SQL with a DO BEGIN END statement. This feature has been available in SAP HANA since HANA SP10.
Below is a sample on how to use DECLARE in HANA SQL in a SQL report:
SQL for copy/paste :)
Declare StartDate DATETIME = [%0];
Declare EndDate DATETIME = [%1];
Where ORDR."DocDate" between StartDate and EndDate;