This can be work for you.
We can get a value from a table, such in that example:
LOAD * INLINE [
"X" , "XValue"
usd , usdValue
eur , eurValue
tl , tlValue
SET vCurrency = '=Minstring("XValue")';
So if you store your result on a table, you can use its columns, and take into a variable.
If we customize to your case, You can try this:
SQL Select min(d_entry_date) As mDate from Tbl_DWR;
SET vCurrency = '=Minstring("mDate")';