On 21/10/10 08:43, Nicholas I wrote:
> Hi,
>
> there are two tables, table1 and table2, each having same column name
> called sn_no,name. i want to update table1 names with table2 where sn_no
> are same.
>
> select * from table1;
> sn_no | name
> -------+-----------
> 1 | ramnad
> 2 | bangalore
> 3 | chennai
>
>
> select * from table2;
> sn_no | name
> -------+-----------
> 1 | Hyderabad
> 2 | Delhi
> 3 | Bombay
>
> Any help ?
>
> I tried with , some of the queries like,
Close. This is surprisingly difficult in standard SQL. PostgreSQL has a
(non-standard) FROM clause you can use though.
BEGIN;
CREATE TABLE table1 (sn int, nm text);
CREATE TABLE table2 (sn int, nm text);
INSERT INTO table1 VALUES (1,'ramnad'),(2,'bangalore'),(3,'chennai');
INSERT INTO table2 VALUES (1,'Hyderabad'),(2,'Delhi'),(3,'Bombay');
UPDATE table1 SET nm = table2.nm
FROM table2
WHERE table1.sn = table2.sn;
SELECT * FROM table1;
ROLLBACK;
Be careful with aliasing the target of the update (table1 in this case).
As another poster has discovered, that counts as another table in your join.
-- Richard Huxton Archonet Ltd