Using Extraction in SQL Server -

i wrote sql query , sample query below:

select      value1,     value2,     value3,     (         select cast(amount1 decimal(17,2))          table1 something...)         - select cast(amount2 decimal(17,2)) table1 something...)     ) 'total purchase'               table1              

but, getting syntax error @ "-" operator.

i tried use "set" statement below

declare     @value1 decimal(17,2),    @value2 decimal(17,2),    @result decimal(17,2)  set value1 = select cast(amount1 decimal(17,2)) table1 something...); set value2 = select cast(amount2 decimal(17,2)) table1 something...); set result = value1 - value2; 

but getting syntax error again,

what can use instead of "-" operator.

thnaks advice,,

there lot of things wrong in sql. try this

select value1,        value2,        value3,        (select cast(amount1 decimal(17, 2))           table1 something...) - (select cast(amount2 decimal(17, 2))                             table1 something...) 'total purchase'   table1 

or

declare @value1 decimal(17, 2),         @value2 decimal(17, 2),         @result decimal(17, 2)  set @value1 = (select cast(amount1 decimal(17, 2))                  table1 something...) set @value2 = (select cast(amount2 decimal(17, 2))                  table1 something...) set @result = @value1 - @value2;