or anyone else, please give advice
let's try it with vlookup
This might work better if I knew what your data looked like, but let's say for an example that sheet 1 has col (a) with your dates in it, and sheet 1 col (b) has your data. On sheet 2, in col (a) you have a subset of the values in sheet 1 col (a). On sheet 2 in cell b2 (assuming a header row) type the following formula
=vlookup(a2,sheet1!a:b,2,false)
the first value is what you're going to lookup, the second is the range in which you're going to look (the farthest left column contains the actual lookup references), the 2 refers to the column in the range (from left to right- that's a little tricky, you have to count the number of columns over, vlookup does not accept normal excel "letter" references for the columns- so you're looking for the second column over, not column B) from which you're going to retrieve values, and the "false" indicates that you only want to retrieve the data from col (B) if the match between sheet 1 a2 and sheet 2 a2 is perfect.
If you need more please post a sample of your data,
Good Luck