SQL: Substitute values between columns - sql

Question

I have a (very simplified) (Oracle) table like this. The row number are only for better understanding, they have no deeper meaning.
Row
value
1
Jim
2
John
3
Mike
Now I find the "error" - the names are messed up. All "Jims" should be renamed to "John", John changes to Mike and Mike changes to Jim.
My first update changes Jim to John.
My second update should change John to Mike.
But the real problem is: Now I have two Johns - the old and the renamed Jim. How to find and modify the "old John" without changing the other?
My idea is to use temp-values:
Jim to temp_John
John to temp_mike
Mike to Jim
temp_John to John
temp_mike to Mike
Good idea? Or are there better ones? Or is it the totally wrong way?
Edit:
I reality, there are not three names, but 700 - 1000 numbers, so
25 to 345
558 to 2
1 to 38
...

Answer 1

Nah, it's just a single UPDATE with a CASE expression:
SQL> select * From test order by crow;
CROW VALU
---------- ----
1 Jim
2 John
3 Mike
SQL> update test set
2 value = case when value = 'Jim' then 'John'
3 when value = 'John' then 'Mike'
4 when value = 'Mike' then 'Jim'
5 end;
3 rows updated.
SQL> select * From test order by crow;
CROW VALU
---------- ----
1 John
2 Mike
3 Jim
SQL>

Answer 2

You can use decode:
update test set value = decode(value,'JIM','JOHN','JOHN','MIKE','MIKE','JIM');
db<>fiddle here
For numbers you can use negative numbers as a temporarity:
update test value = decode(value, 65537, -7777776777777, value);
update test value = decode(value, 7777776777777, -45, value);
update test value = decode(value, 45, -65537, value);
update test set value = abs(value);
This way you can have as many numbers as you want as it uses one query per number.
updated db<>fiddle here for numbers example

Answer 3

You should create a table with two columns:
create table value_pairs
(old_value integer,
new_value integer,
primary key (old_value));
After creating the table you have to insert the old and new values:
insert into value_pairs values (1, 2);
insert into value_pairs values (2, 3);
etc.
Finally run this SQL statement:
update your_table t
set value =
(select new_value
from value_pairs p
where p.old_value = t.value);
In this case you don't have to write long case or decode statements.