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Question

Hello,
Here's my query...
SELECT row_id, item_code, mfg_date, mfg_qty, good_qty, COUNT(*) OVER
      PARTITION BY item_code
      ORDER BY mfg_date
    ) cnt
  FROM
    table_xHere's a sample output of my sample query above
CREATE TABLE table_x
(     row_id     NUMBER     PRIMARY KEY
,     item_code     varchar(30)
,     mfg_date     DATE
,     mfg_qty     NUMBER
,     good_qty     NUMBER
,     cnt           NUMBER
INSERT INTO table_x (row_id, item_code, mfg_date, mfg_qty, good_qty, cnt) VALUES (1,  A-001, DATE '2010-08-20',200,195,1);
INSERT INTO table_x (row_id, item_code, mfg_date, mfg_qty, good_qty, cnt) VALUES (2,  A-002, DATE '2010-08-20',300,290,1);
INSERT INTO table_x (row_id, item_code, mfg_date, mfg_qty, good_qty, cnt) VALUES (3,  A-002, DATE '2010-08-21',400,200,2);
INSERT INTO table_x (row_id, item_code, mfg_date, mfg_qty, good_qty, cnt) VALUES (4,  A-002, DATE '2010-08-22',500,450,3);
INSERT INTO table_x (row_id, item_code, mfg_date, mfg_qty, good_qty, cnt) VALUES (5,  A-002, DATE '2010-08-23',100,100,4);
COMMIT;Question:
I need to create another column from this table, let's name it column_x. If the cnt column is 1, mark column_x as false, else...
Let's take this example... If I'm looking at item 3, I need to retrieve the mfg_qty and good_qty column of item 2. If the mfg_qty of item 2 * 0.9 <= good_qty of item 2, mark the column_x of item 3 as true, else false.
Following the table above, my table now should be...
CREATE TABLE table_x
(     row_id     NUMBER     PRIMARY KEY
,     item_code     varchar(30)
,     mfg_date     DATE
,     mfg_qty     NUMBER
,     good_qty     NUMBER
,     cnt           NUMBER
,       column_x   varchar(5)
INSERT INTO table_x (row_id, item_code, mfg_date, mfg_qty, good_qty, cnt, column_x) VALUES (1,  A-001, DATE '2010-08-20',200,195,1,'false');
INSERT INTO table_x (row_id, item_code, mfg_date, mfg_qty, good_qty, cnt, column_x) VALUES (2,  A-002, DATE '2010-08-20',300,290,1,'false');
INSERT INTO table_x (row_id, item_code, mfg_date, mfg_qty, good_qty, cnt, column_x) VALUES (3,  A-002, DATE '2010-08-21',400,200,2,'true');
INSERT INTO table_x (row_id, item_code, mfg_date, mfg_qty, good_qty, cnt, column_x) VALUES (4,  A-002, DATE '2010-08-22',500,450,3,'false');
INSERT INTO table_x (row_id, item_code, mfg_date, mfg_qty, good_qty, cnt, column_x) VALUES (5,  A-002, DATE '2010-08-23',100,100,4,'true');
COMMIT;Let me know if you need more clarifications. :)
Edited by: Claude2005 on Nov 9, 2010 7:32 PM
Reworked my post

Answer 1

Claude2005 wrote:
Question:
I need to create another column from this table, let's name it column_x. If the cnt column is 1, mark column_x as false, else...
Let's take this example... If I'm looking at item 3, I need to retrieve the mfg_qty and good_qty column of item 2. If the mfg_qty of item 2 * 0.9 <= good_qty of item 2, mark the column_x of item 3 as true, else false.Thanks for posting DDL and sample data.
Aren't those two conditions (to derive value of column_x) different? Which one are you interested in, either or both?
Assuming you want to derive the value for column_x based on second condition above, how about following?
SELECT row_id, item_code, mfg_date, mfg_qty, good_qty,
           case when lag(mfg_qty) over (order by mfg_date) * 0.9 <= lag(good_qty) over (order by mfg_date)
           then 'true'
           else 'false'
           end as column_x
  FROM
    table_xI don't have access to a database now so above is not tested.
You may also want to consider what should happen when mfg_date and/or item_code are not unique