sql - Oracle: update column with values from another table -

i added new column existing table. want populate value retrieve table.

table: export

name | email | employeeid | userid 

table: user

id |  name  | email  | idnumber 

the new column export.userid, want equal out user.id. please note id , idnumber are not same - idnumber stores employeeid while id auto-increment pk. user.idnumber equal export.employeeid.

i want populate export.userid user.id when export.employeeid = user.idnumber.

how can oracle-compatible sql-code?

i tried following, throws me error.

update export      set userid = ( select id                  user                 user.idnumber = export.employeeid                   , user.email = export.email)   exists( select 1              user             user.idnumber = export.employeeid                , user.email = export.email)  

but error

[error] execution (2: 19): ora-01427: single-row subquery returns more 1 row 

probably, subquery returns more 1 row given email , idnumber:

select id                  user                 user.idnumber = export.employeeid                   , user.email = export.email 

try using distinct exclude duplicates:

select distinct id                  user                 user.idnumber = export.employeeid                   , user.email = export.email 

or add sample data question. unique key of tables user , export?