Sum with multiple references

Need to create a formula similar to MS Excel.
Basic logic is:
Sum all values in C where A = x and B = y
This is done to produce a sheet of consolidated sums from a sheet with an ongoing set of log entries.
LOG:
DATE TIME ACTIVITY
2013-01-06 :25 finance
2013-01-06 :42 systems
2013-01-06 1:13 finance
2013-01-06 :23 systems

SUMS:
DATE finance systems
2013-01-06 1:38 1:05

So the formula becomes something like:
sumif(LOG.$A:A=$A2 AND LOG.$C:C=$B$1; LOG.$B$2:B)

Any suggestions?

Take a look to this thread.

Should mariosv’s answer doesn’t help you, please provide some more information on what do you want to do.

Does your “log” or “LOG” refer to logarithm or loggin date and time information?

Why do you need “sumif” is “sum” not sufficient?

Can you create a short example table reflecting your data arrangement in your spreadsheet?