Can I use Declare in SAP B1 v9 Hana Query Generator?

I am getting errors attempting to create a declare line in a query in Query Generator. I am told this works in My Sql..

/*SELECT * FROM "OINV" T0*/

Declare @FromDate timestamp;

Set @FromDate = /* SELECT T0."DocDate" from OINV T0 Where T0."DocDate" = */ '[%0]';

SELECT * FROM "OINV"

WHERE "DocDate" > @FromDate

-- error message says incorrect syntax near @ line 3 col 3

what syntax do i need here or does declare not work in Query Manager as it does in other products?