[SQL] Update question

[Fay Du]

Hi all:   I have a table like this:   Table cost Id  edge_id    cost 1       30         101.4 2       30          null 3       40          500.2 4       40           null 5        45          300.7 6        45           null   I want to set cost value with same edge_id by same value. The existing values are calculated by calling a function (calculate edge length). I can calculate the value by same function, but the function was slow. I wander if I can use update statement to set the second value with same edge_id. Thanks in advance for your help.   Fay