数据表计算：按日期过滤

Question

I have a datatable with 2 columns: "amount" and "date"

I want to sum "amount" by month & year.

I am trying this:

_tAmount = myDT.Compute("sum(amount)", "date LIKE '%/" & i & "/" & _year & "'")

where:

• var i equals a nº month ( 1 to 12)
• var _year equals nº year (example: 2011)

But not displays any results....How I can do it? What is wrong?

I am working with the spanish format (example day/month/year). But I have tried with the english format (month/day/year) and no results too.

This is on VB.NET 2008.

Answer 1

I don't thing date works with LIJKE, why don't you use:

dim startdt as date =  new date(_year, month, 1)
dim enddt as date = startdt.addmonth(1).adddays(-1)
_tAmount = myDT.Compute("sum(amount)", "date >= " & startdt & " AND date <= " & enddt)

This is out the top of my head, so check it yourself, but you should get the idea. Also, I use mostly the # sign around the dates to force english notation, but you'll have to experiment yourself.