Decode function in Update statement

Question

Hello everyone,
I'm trying to write a query where I can update a pastdue_fees column in a book_trans table based on a difference between return_dte and due_dte columns.
I am using Oracle SQL. This is what I have so far for my decode function:
SQL> SELECT
2 DECODE(SIGN((return_dte - due_dte)*2),
3 '-1', '0',
4 '1', '12', 'Null')
5 FROM book_trans;
DECO
Null
12
Null
0
So the logic is that if the sign is -1, the value in return_dte column should be 0; if it's +1 then it's 12 and everything else is Null.
So now, I need to enter my decode function into the update statement to update the columns. However, I get error messages.
The logic should be:
UPDATE book_trans SET PastDue_fees = decode(expression)
I've given it a couple of different tries with the following results:
SQL> UPDATE book_trans
2 SET pastdue_fees = SELECT
3 DECODE(SIGN((return_dte - due_dte)*2),
4 '-1', '0',
5 '1', '12', 'Null')
6 FROM book_trans;
SET pastdue_fees = SELECT
ERROR at line 2:
ORA-00936: missing expression
SQL> UPDATE book_trans
2 SET pastdue_fees =
3 DECODE(SIGN((return_dte - due_dte)*2),
4 '-1', '0',
5 '1', '12', 'Null')
6 FROM book_trans;
FROM book_trans
ERROR at line 6:
ORA-00933: SQL command not properly ended
Any help or tips would be greatly appreciated as I've been taking SQL for about six weeks and not very proficient!
Thanks!

Answer 1

882300 wrote:
Hello everyone,
I'm trying to write a query where I can update a pastdue_fees column in a book_trans table based on a difference between return_dte and due_dte columns.
I am using Oracle SQL. This is what I have so far for my decode function:
SQL> SELECT
2 DECODE(SIGN((return_dte - due_dte)*2),
3 '-1', '0',
4 '1', '12', 'Null')
5 FROM book_trans;
DECO
Null
12
Null
0
So the logic is that if the sign is -1, the value in return_dte column should be 0; if it's +1 then it's 12 and everything else is Null.
So now, I need to enter my decode function into the update statement to update the columns. However, I get error messages.
The logic should be:
UPDATE book_trans SET PastDue_fees = decode(expression)
I've given it a couple of different tries with the following results:
SQL> UPDATE book_trans
2 SET pastdue_fees = SELECT
3 DECODE(SIGN((return_dte - due_dte)*2),
4 '-1', '0',
5 '1', '12', 'Null')
6 FROM book_trans;
SET pastdue_fees = SELECT
ERROR at line 2:
ORA-00936: missing expression
SQL> UPDATE book_trans
2 SET pastdue_fees =
3 DECODE(SIGN((return_dte - due_dte)*2),
4 '-1', '0',
5 '1', '12', 'Null')
6 FROM book_trans;
FROM book_trans
ERROR at line 6:
ORA-00933: SQL command not properly ended
Any help or tips would be greatly appreciated as I've been taking SQL for about six weeks and not very proficient!
Thanks!If you really really really want to update the entire table, the syntax would be...
UPDATE book_trans
   SET
      pastdue_fees  = DECODE(SIGN((return_dte - due_dte)*2), -1, 0, 1, 12, Null);I took out all the single quotes. If you actually have a string column and you're storing entirely numbers in it then it should be declared as a NUMBER column and not a character (varchar2) column.
ALWAYS use the proper data type, it'll save you a ton of headaches in the future.
Also, since you're new to the forum, please read the FAQ so you learn the etiquette and what not.
http://wikis.sun.com/display/Forums/Forums+FAQ