sql - insert column from one table into another -

i have 2 tables: set1 , searchinfo. this:

set1 searchid | position 3          1 1          7 3          4  searchinfo searchid | searchdate 1          6 2          8 3          9 

i want add column searchdate set1 , use searchid key. have tried:

alter table set1 add column searchdate1 datetime; insert set1 (searchdate1) select b.searchdate set1 left outer join searchinfo b on a.searchid=b.searchid;  

however,

set1 searchid | position | searchdate1 3          1           1          7           3          4                       x                       x                       x 

as oppose :

set1 searchid | position | searchdate1 3          1          9 1          7          6 3          4          9 

what want : update column have made. not need insert anything

update set1 set searchdate = si.searchdate set1 s inner join searchinfo si s.searchid = si.searchid