[sql] Oracle SQL: Update a table with data from another table

Table 1:

id    name    desc
-----------------------
1     a       abc
2     b       def
3     c       adf

Table 2:

id    name    desc
-----------------------
1     x       123
2     y       345

In oracle SQL, how do I run an sql update query that can update Table 1 with Table 2's name and desc using the same id? So the end result I would get is

Table 1:

id    name    desc
-----------------------
1     x       123
2     y       345
3     c       adf

Question is taken from update one table with data from another, but specifically for oracle SQL.

Here seems to be an even better answer with 'in' clause that allows for multiple keys for the join:

update fp_active set STATE='E', 
   LAST_DATE_MAJ = sysdate where (client,code) in (select (client,code) from fp_detail
  where valid = 1) ...

The full example is here: http://forums.devshed.com/oracle-development-96/how-to-update-from-two-tables-195893.html - from web archive since link was dead.

The beef is in having the columns that you want to use as the key in parentheses in the where clause before 'in' and have the select statement with the same column names in parentheses. where (column1,column2) in ( select (column1,column2) from table where "the set I want" );

Update table set column = (select...)

never worked for me since set only expects 1 value - SQL Error: ORA-01427: single-row subquery returns more than one row.

here's the solution:

BEGIN
For i in (select id, name, desc from table1) 
LOOP
Update table2 set name = i.name, desc = i.desc where id = i.id;
END LOOP;
END;

That's how exactly you run it on SQLDeveloper worksheet. They say it's slow but that's the only solution that worked for me on this case.

try

UPDATE Table1 T1 SET
T1.name = (SELECT T2.name FROM Table2 T2 WHERE T2.id = T1.id),
T1.desc = (SELECT T2.desc FROM Table2 T2 WHERE T2.id = T1.id)
WHERE T1.id IN (SELECT T2.id FROM Table2 T2 WHERE T2.id = T1.id);

BEGIN
For i in (select id, name, desc from table2) 
LOOP
Update table1 set name = i.name, desc = i.desc where id = i.id and (name is null or desc is null);
END LOOP;
END;

Try this:

MERGE INTO table1 t1
USING
(
-- For more complicated queries you can use WITH clause here
SELECT * FROM table2
)t2
ON(t1.id = t2.id)
WHEN MATCHED THEN UPDATE SET
t1.name = t2.name,
t1.desc = t2.desc;

If your table t1 and it's backup t2 have many columns, here's a compact way to do it.

In addition, my related problem was that only some of the columns were modified and many rows had no edits to these columns, so I wanted to leave those alone - basically restore a subset of columns from a backup of the entire table. If you want to just restore all rows, skip the where clause.

Of course the simpler way would be to delete and insert as select, but in my case I needed a solution with just updates.

The trick is that when you do select * from a pair of tables with duplicate column names, the 2nd one will get named _1. So here's what I came up with:

  update (
    select * from t1 join t2 on t2.id = t1.id
    where id in (
      select id from (
        select id, col1, col2, ... from t2
        minus select id, col1, col2, ... from t1
      )
    )
  ) set col1=col1_1, col2=col2_1, ...