sql - How would I use a CURSOR to iterate through a list of values to do a calculation for each value? -

i have searched , searched way i'm trying do, haven't found solution yet. have dates stored in table so:

dates      code    sum 1-15-2015  aaa     (to calculated) 2-2-2016   bbb     (to calculated) 11-23-2015 ccc     (to calculated) 

the sum each record in table calculated based on date in date column. want use date date column parameter of sorts calculation each record in table. assume cursor best approach, new sql , don't how implement such functionality. example's sake, can totally make sum calculation. it's trivial, anyway. have looked @ several examples elsewhere, i've had no luck. appreciated.

the sum calculation

the sum calculated pulling values out of database, via pass-through query, within date range. date range determined date in dates column of example table. date range date value in dates column today's date (getdate()). need know how change left date date in dates column each record in sample table. efficiency key.

my answer generic, you'll need either outer apply or cross apply depending on if want filter null values or not.

the syntax similar this:

select  a.dates, a.code, x.sum    yourtable   outer apply (     select  sum(b.stufftosum)    sum        otherdatabase.otherschema.othertable    b       b.date between a.dates , getdate() ) x 

your outer apply logic should match actual logic you're using, i'm using example showing how can date range date in first table getdate().

using outer apply, if there no values in other table fall in date range, return null. in case of cross apply, entire record filtered out (this behaviour similar of inner , outer joins).