How to set different values only to one column

Is it possible to set different values to one column only with one sql command?

With

sql = "UPDATE Table set col = val1 where Pos = y1"
ExecuteSQL(sql)
sql = "UPDATE Table set col = val2 where Pos = y2"
ExecuteSQL(sql)
sql = "UPDATE Table set col = val3 where Pos = y3"
ExecuteSQL(sql)

... I can set different values to one column, but that is very slow! -- and I have to set up to 500 different values to one column at different positions.

For any reply thanks in advance.

dlbergh