In PLSQL, what is the UPDATE statement to replace column values from one table to column values of another?

Question

eg. table1 and table2 both have columns called contactid;
What is the UPDATE command to convert all the values from table1.contactid to table2.contactid in PLSQL?

Answer 1

Update table2.contactid set table2.contactid = (select table1.contactid from table1);

committ;

If you have another condition to concatinate the two tables, then you can write the condition in the select statement.

Answer 2

What is the primary key? Supposing it is keyval, then:

update table1 t1
set t1.contactid = (select contactid from table2 t2
where t1.keyval=t2.keyval)