Question

I have table TB1 which has the following cols:

ID        |    date  
---------------------
1         |    12-JUL-10
2         |    12-JUL-10
3         |    12-JUL-10
4         |    12-JUL-10
.
.
.
10000     |    12-JUL-10

table2

ID        |    date  
---------------------
1         |    12-JAN-09
2         |    12-JUL-09
3         |    12-JUL-09
4         |    12-JUL-08
.
.
.
5800      |    12-JUL-08

How to update the table2’s date which has similar ID as table1.

Thanks 🙂

Answer 1

In general

   UPDATE table2 t2
       SET date_col = (SELECT t1.date_col
                         FROM table1 t1
                        WHERE t1.id = t2.id)
     WHERE EXISTS (
        SELECT 1
          FROM table1 t1
         WHERE t1.id = t2.id )

If you can be guaranteed that every ID in table2 exists in table1 (or if you want the date_col set to NULL if there is no match), you can eliminate the WHERE EXISTS. But generally you only want to do an update if there is a matching record.