I have a table in mysql database this data.
id date close previous_close
1 07-10-2020 200 300
2 06-10-2020 300 1000
3 05-10-2020 0 1000
4 04-10-2020 1000 15
I've had a look at using the lag() function but can't get my head round it. How can I craft a query such that the calculated column previous_close obtains the most recently available value in the close column where it's not zero?
Here is one way:
WITH cte AS (
SELECT *,
MAX(CASE WHEN close > 0 THEN date END) OVER
(ORDER BY date ROWS BETWEEN UNBOUNDED PRECEDING AND 1 PRECEDING) AS last_date
FROM yourTable
)
SELECT
t1.id,
t1.date,
t1.close,
t2.close AS previous_close
FROM cte t1
LEFT JOIN yourTable t2
ON t2.date = t1.last_date
ORDER BY t1.date DESC;
The strategy here is that the CTE finds the latest date corresponding to a non zero close occurring strictly before each given row, as sorted by date. Then, all we have to do is to join this CTE back to your original table to find the actual matching latest previous close value.
Related
I am trying to select multiple rows of data into one row through multiple columns which will change dynamically.
This is in Oracle database. I want to count repeated work done by the LEAD_TECHNISIAN_ID within a duration. If the difference of last work delivery date and new work receive date is 15 or below 15 then LEAD_TECHNISIAN_ID has one repeated work.
List item
SELECT *
FROM (WITH CTE AS (
SELECT ROW_NUMBER () OVER (ORDER BY ID) AS RW,
RECEIVED_DATE,
DELIVERY_DATE,
SERVICE_NO,
LEAD_TECHNISIAN_ID,
ID,
SERVICE_CENTER
FROM ( SELECT cc.SERVICE_CENTER,
CC.ID,
CC.BARCODE,
TRUNC (cc.CREATED_DATE) RECEIVED_DATE,
TRUNC (CC.DELIVERY_DATE) DELIVERY_DATE,
cc.SERVICE_NO,
CC.LEAD_TECHNISIAN_ID
FROM customer_complains cc
WHERE cc.BARCODE IN (SELECT BARCODE
FROM (SELECT BARCODE,
COUNT (BARCODE)
FROM customer_complains c
WHERE c.BARCODE <> 'UNDEFINE'
AND C.BARCODE = NVL ('351950102757821', BARCODE)
AND c.SEGMENT3 = NVL ('',c.SEGMENT3)
AND c.SEGMENT3 IN (SELECT SEGMENT3
FROM ITEM_MST
WHERE PRODUCT_GROUP = NVL ('',PRODUCT_GROUP))
GROUP BY c.BARCODE
HAVING COUNT (c.BARCODE) >1))
ORDER BY ID DESC)
ORDER BY ID DESC)
SELECT a.id,
a.DELIVERY_DATE,
a.RECEIVED_DATE,
b.RECEIVED_DATE PRE_RCV,
b.DELIVERY_DATE PRE_DEL,
(a.RECEIVED_DATE - b.DELIVERY_DATE) AS DIFF,
a.SERVICE_NO,
a.LEAD_TECHNISIAN_ID,
b.LEAD_TECHNISIAN_ID PRE_TECH --, a.DELIVERY_DATE
FROM CTE a
LEFT JOIN CTE b ON a.RW = b.RW + 1
)
WHERE DIFF <= 15
Here is the output for a specific barcode. but when I try for All the barcode I have in My Customer_complains table. The query provides irrelevant output.
Currently your code is giving numbers 1,2,3,4... to rows irrespective of LEAD_TECHNISIAN_ID and then you are joining it with RW. It will not consider LEAD_TECHNISIAN_ID while giving row numbers.
RW must start with 1 for each LEAD_TECHNISIAN_ID.
You just need to change calculation of RW as following:
ROW_NUMBER () OVER (PARTITION BY LEAD_TECHNISIAN_ID ORDER BY ID) AS RW
Cheers!!
In my database I have a table with column that indicates the code of each record ( aside from ID column ). this field is unique and each time the user tries to insert a record into the table, the first unused code should be assigned to the record. Now the table has the column of codes with the following order :
+------+
code
+------+
1
+------+
2
+------+
3
+------+
5
+------+
I want a query to return 4 as the result.
Note that this query is highly frequent in my system and the best query with minimum execution time will be appreciated.
Is using a self-join acceptable? If so:
-- your test data:
WITH data AS (SELECT 1 AS code FROM DUAL
UNION SELECT 2 FROM DUAL
UNION SELECT 3 FROM DUAL
UNION SELECT 5 FROM DUAL)
-- request:
SELECT COALESCE(MIN(d1.code+1),1)
FROM data d1 LEFT JOIN data d2 ON d1.code+1 = d2.code
WHERE d2.code IS NULL;
This will build the list of data.code without a successor. And using MIN(...+1) you will get the first empty slot. I used COALESCE(...) in order to handle the specific case where there isn't any entry in the data table.
And alternate form using a sequence generator might lead to better performances as is does not require the whole table to be traversed in order to perform the aggregate function MIN():
-- your test data:
WITH data AS (SELECT 1 AS code FROM DUAL
UNION SELECT 5 FROM DUAL
UNION SELECT 2 FROM DUAL
UNION SELECT 3 FROM DUAL)
-- request:
SELECT T.code FROM (SELECT d1.code
FROM (SELECT LEVEL code FROM DUAL CONNECT BY LEVEL < 9999) d1 LEFT JOIN data d2
ON d1.code = d2.code
WHERE d2.code IS NULL
ORDER BY d1.code ASC
) T WHERE ROWNUM < 2
The drawback is you now have an upper limit hard-coded. It might be dynamically inferred from the data table though. So is is not really blocking. I let you compare timings yourself.
this field is unique and each time the user tries to insert a record into the table, the first unused code should be assigned to the record
Please note however this will lead to a race condition if two concurrent sessions try to insert a row at the same time. Given your example, they will both try to insert a row with code = 4 -- obviously both will not succeed in doing so as your column is unique...
I recently use the code below:
SELECT t1.id+1
FROM table t1
LEFT OUTER JOIN table t2 ON (t1.id + 1 = t2.id)
WHERE t2.id IS NULL
/* and rownum = 1 Need to use a sub select if you want this to work */
ORDER BY t1.id;
I run it every time that I need to insert a new row and use the minimum unused id.
I hope it works for your purposes.
select level unusedval from dual connect by level < 10
minus
select tno from t2);
you can change level condition dependents on max value.
Problem: I need write stored procedure(s) that will return result set of a single page of rows and the number of total rows.
Solution A: I create two stored procedures, one that returns a results set of a single page and another that returns a scalar -- total rows. The Explain Plan says the first sproc has a cost of 9 and the second has a cost of 3.
SELECT *
FROM ( SELECT ROW_NUMBER() OVER ( ORDER BY D.ID DESC ) AS RowNum, ...
) AS PageResult
WHERE RowNum >= #from
AND RowNum < #to
ORDER BY RowNum
SELECT COUNT(*)
FROM ...
Solution B: I put everything in a single sproc, by adding the same TotalRows number to every row in the result set. This solution feel hackish, but has a cost of 9 and only one sproc, so I'm inclined to use this solution.
SELECT *
FROM ( SELECT ROW_NUMBER() OVER ( ORDER BY D.ID DESC ) RowNum, COUNT(*) OVER () TotalRows,
WHERE RowNum >= from
AND RowNum < to
ORDER BY RowNum;
Is there a best-practice for pagination in Oracle? Which of the aforementioned solutions is most used in practice? Is any of them considered just plain wrong? Note that my DB is and will stay relatively small (less than 10GB).
I'm using Oracle 11g and the latest ODP.NET with VS2010 SP1 and Entity Framework 4.4. I need the final solution to work within the EF 4.4. I'm sure there are probably better methods out there for pagination in general, but I need them working with EF.
If you're already using analytics (ROW_NUMBER() OVER ...) then adding another analytic function on the same partitioning will add a negligible cost to the query.
On the other hand, there are many other ways to do pagination, one of them using rownum:
SELECT *
FROM (SELECT A.*, rownum rn
FROM (SELECT *
FROM your_table
ORDER BY col) A
WHERE rownum <= :Y)
WHERE rn >= :X
This method will be superior if you have an appropriate index on the ordering column. In this case, it might be more efficient to use two queries (one for the total number of rows, one for the result).
Both methods are appropriate but in general if you want both the number of rows and a pagination set then using analytics is more efficient because you only query the rows once.
In Oracle 12C you can use limit LIMIT and OFFSET for the pagination.
Example -
Suppose you have Table tab from which data needs to be fetched on the basis of DATE datatype column dt in descending order using pagination.
page_size:=5
select * from tab
order by dt desc
OFFSET nvl(page_no-1,1)*page_size ROWS FETCH NEXT page_size ROWS ONLY;
Explanation:
page_no=1
page_size=5
OFFSET 0 ROWS FETCH NEXT 5 ROWS ONLY - Fetch 1st 5 rows only
page_no=2
page_size=5
OFFSET 5 ROWS FETCH NEXT 5 ROWS ONLY - Fetch next 5 rows
and so on.
Refrence Pages -
https://dba-presents.com/index.php/databases/oracle/31-new-pagination-method-in-oracle-12c-offset-fetch
https://oracle-base.com/articles/12c/row-limiting-clause-for-top-n-queries-12cr1#paging
This may help:
SELECT * FROM
( SELECT deptno, ename, sal, ROW_NUMBER() OVER (ORDER BY ename) Row_Num FROM emp)
WHERE Row_Num BETWEEN 5 and 10;
A clean way to organize your SQL code could be trough WITH statement.
The reduced version implements also total number of results and total pages count.
For example
WITH SELECTION AS (
SELECT FIELDA, FIELDB, FIELDC FROM TABLE),
NUMBERED AS (
SELECT
ROW_NUMBER() OVER (ORDER BY FIELDA) RN,
SELECTION.*
FROM SELECTION)
SELECT
(SELECT COUNT(*) FROM NUMBERED) TOTAL_ROWS,
NUMBERED.*
FROM NUMBERED
WHERE
RN BETWEEN ((:page_size*:page_number)-:page_size+1) AND (:page_size*:page_number)
This code gives you a paged resultset with two more fields:
TOTAL_ROWS with the total rows of your full SELECTION
RN the row number of the record
It requires 2 parameter: :page_size and :page_number to slice your SELECTION
Reduced Version
Selection implements already ROW_NUMBER() field
WITH SELECTION AS (
SELECT
ROW_NUMBER() OVER (ORDER BY FIELDA) RN,
FIELDA,
FIELDB,
FIELDC
FROM TABLE)
SELECT
:page_number PAGE_NUMBER,
CEIL((SELECT COUNT(*) FROM SELECTION ) / :page_size) TOTAL_PAGES,
:page_size PAGE_SIZE,
(SELECT COUNT(*) FROM SELECTION ) TOTAL_ROWS,
SELECTION.*
FROM SELECTION
WHERE
RN BETWEEN ((:page_size*:page_number)-:page_size+1) AND (:page_size*:page_number)
Try this:
select * from ( select * from "table" order by "column" desc ) where ROWNUM > 0 and ROWNUM <= 5;
I also faced a similar issue. I tried all the above solutions and none gave me a better performance. I have a table with millions of records and I need to display them on screen in pages of 20. I have done the below to solve the issue.
Add a new column ROW_NUMBER in the table.
Make the column as primary key or add a unique index on it.
Use the population program (in my case, Informatica), to populate the column with rownum.
Fetch Records from the table using between statement. (SELECT * FROM TABLE WHERE ROW_NUMBER BETWEEN LOWER_RANGE AND UPPER_RANGE).
This method is effective if we need to do an unconditional pagination fetch on a huge table.
Sorry, this one works with sorting:
SELECT * FROM (SELECT ROWNUM rnum,a.* FROM (SELECT * FROM "tabla" order by "column" asc) a) WHERE rnum BETWEEN "firstrange" AND "lastrange";
I have a stored procedure which I use to return the earliest available date in a column of dates. I need to only return the earliest, and currently am using date arithmetic to reduce the number of returned rows. However, doing it this way, my procedure gets stuck in a loop of the first two top returned values, meaning I have several rows which are never read. Could somebody please let me know where I need to use the MIN function in the following WHERE clause, please? Thanks:
SELECT **COLS**
INTO **VARS**
FROM **TABLE**
INNER JOIN **TABLE TO JOIN**
ON **JOIN TARGET**
WHERE ROWNUM = 1 AND LASTREADTIME < SYSDATE - (30/86400)
ORDER BY LASTREADTIME DESC;
if you only need the earliest date
SELECT MIN(LastReadTime)
INTO **VARS**
FROM table
if you need other datas
SELECT t2.col1, t1.col1, t1.col2, t1.LastTreadTime
INTO **VARS**
FROM table t1
JOIN table2 t2 on t1.col1 = t2.col1
WHERE t1.LastReadTime = (SELECT MIN(t2.LastReadTime) FROM table t2);
I have an account where interest is debited corresponding to each account as below
amount Date
2 01-01-2012
5 02-01-2012
2 05-01-2012
1 07-01-2012
If the total credit in the account is 8. Ineed a query to find till what dates interest the credit amount can adjust.
Here the query should give output as 02-01-2012(2+5 < 8). I know this can be handled through cursor. But is there any method to write this as a single query in ORACLE.
SELECT pdate
FROM (
SELECT t.*,
LAG(date) OVER (ORDER BY date) AS pdate
8 - SUM(amount) OVER (ORDER BY date ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) AS diff
FROM mytable t
ORDER BY
date
)
WHERE diff < 0
AND rownum = 1
Not knowing the structure of your table, here's a guess:
SELECT date from your_table
GROUP BY AMOUNT
HAVING SUM(AMOUNT) < 8
Note: this is LESS THAN 8. Change the conditional as appropriate.
Doesn't do the (2+5)<8 thing yet:
select max(cum_sum), max(date)
from (
select date,
sum(amount) over (order by date) cum_sum
) where cum_sum < 8