calculating values from one database table and the textbox value

create database demo1
use demo1
create table leve(userId int,maxLeve int,TotalTakenLeve int)
insert into leve values(1,10,2)
insert into leve values(2,10,6)
insert into leve values(3,10,2)
insert into leve values(4,10,9)
insert into leve values(5,10,5)
insert into leve values(6,10,2)
insert into leve values(7,10,1)

select * from leve
--get maximum leve
select maxleve from leve where userid='1'
--get remaining leve
select (maxLeve-(TotalTakenLeve+Textbox.text))as remainingLeve from leve where userid='1'--textbox.text is no of day given from Winform
--for example textbox.text=2 then
select (maxLeve-(TotalTakenLeve+2)) as remainingLeve from leve where userid='1'
--result remaining leve is::::: 6
--if result is 0 then there are no leve for give user or employee