Sqlite Increment column value based on previous row's value - sqlite

How do I increment a column value based on previous column value in Sqlite? I need to do this for 1000+ rows. I have data in the first row say 100. I need to increment the next 1000 rows by 2.
Row# ColName
1 100
2 102
3 104
4 106
I tried something like this:
Update Table SET ColName = (Select max(ColName ) from Table ) + 2 but this puts 102 in all columns.

Assuming that this table has a rowid column, it is possible to count how many previous rows there are:
UPDATE MyTable
SET ColName = (SELECT MAX(ColName)
FROM MyTable
) +
(SELECT COUNT(*)
FROM MyTable AS Previous
WHERE Previous.rowid < MyTable.rowid
) * 2
WHERE ColName IS NULL

Related

SQLITE get next row after ORDERBY

I need to get the next row from an ORDERBY query
I have 2 columns, ID(Primary key), Age(float) in a table T and I need something like the following
SELECT ID FROM T WHERE !> (inputted ID) + 1 rowID/Next row <! ORDERBY Age (then primary key, but I suspect if the Age values are the same SQLite would default to order by primary key anyway) LIMIT 1
Essentially it would select the next row after the inputted ID in the ordered table, its the next row / rowID + 1 I am not sure how to get.
As suggested here is a data set as an example
https://dbfiddle.uk?rdbms=sqlite_3.27&fiddle=19685ac20cc42041a59d318a01a2010f
ID Age
1 12.2
2 36.8
3 22.5
4 41
5 16.7
I am attempting to get the the following row from the ordered (by age) list given a specific ID
ID Age
1 12.2
5 16.7
3 22.5
2 36.8
4 41
Something similar to
SELECT ID FROM OrderedInfo WHERE ID = 5 ORDER BY Age ASC LIMIT 1 OFFSET 1;
My expected result would be '3' from the example data above
I have expanded the data set to include duplicate entries as I didn't implicitly state it could have such data - as such forpas answer works for the first example with no duplicate entries - thanks for your help
https://dbfiddle.uk?rdbms=sqlite_3.27&fiddle=f13d7f5a44ba414784547d9bbdf4997e
Use a subquery for the ID that you want in the WHERE clause:
SELECT *
FROM OrderedInfo
WHERE Age > (SELECT Age FROM OrderedInfo WHERE ID = 5)
ORDER BY Age LIMIT 1;
See the demo.
If there are duplicate values in the column Age use a CTE that returns the row that you want and join it to the table so that you expand the conditions:
WITH cte AS (SELECT ID, Age FROM OrderedInfo WHERE ID = 5)
SELECT o.*
FROM OrderedInfo o INNER JOIN cte c
ON o.Age > c.Age OR (o.Age = c.Age AND o.ID > c.ID)
ORDER BY o.Age, o.ID LIMIT 1;
See the demo.

Creating even ranges based on values in an oracle table

I have a big table which is 100k rows in size and the PRIMARY KEY is of the datatype NUMBER. The way data is populated in this column is using a random number generator.
So my question is, can there be a possibility to have a SQL query that can help me with getting partition the table evenly with the range of values. Eg: If my column value is like this:
1
2
3
4
5
6
7
8
9
10
And I would like this to be broken into three partitions, then I would expect an output like this:
Range 1 1-3
Range 2 4-7
Range 3 8-10
It sounds like you want the WIDTH_BUCKET() function. Find out more.
This query will give you the start and end range for a table of 1250 rows split into 20 buckets based on id:
with bkt as (
select id
, width_bucket(id, 1, 1251, 20) as id_bucket
from t23
)
select id_bucket
, min(id) as bkt_start
, max(id) as bkt_end
, count(*)
from bkt
group by id_bucket
order by 1
;
The two middle parameters specify min and max values; the last parameter specifies the number of buckets. The output is the rows between the minimum and maximum bows split as evenly as possible into the specified number of buckets. Be careful with the min and max parameters; I've found poorly chosen bounds can have an odd effect on the split.
This solution works without width_bucket function. While it is more verbose and certainly less efficient it will split the data as evenly as possible, even if some ID values are missing.
CREATE TABLE t AS
SELECT rownum AS id
FROM dual
CONNECT BY level <= 10;
WITH
data AS (
SELECT id, rownum as row_num
FROM t
),
total AS (
SELECT count(*) AS total_rows
FROM data
),
parts AS (
SELECT rownum as part_no, total.total_rows, total.total_rows / 3 as part_rows
FROM dual, total
CONNECT BY level <= 3
),
bounds AS (
SELECT parts.part_no,
parts.total_rows,
parts.part_rows,
COALESCE(LAG(data.row_num) OVER (ORDER BY parts.part_no) + 1, 1) AS start_row_num,
data.row_num AS end_row_num
FROM data
JOIN parts
ON data.row_num = ROUND(parts.part_no * parts.part_rows, 0)
)
SELECT bounds.part_no, d1.ID AS start_id, d2.ID AS end_id
FROM bounds
JOIN data d1
ON d1.row_num = bounds.start_row_num
JOIN data d2
ON d2.row_num = bounds.end_row_num
ORDER BY bounds.part_no;
PART_NO START_ID END_ID
---------- ---------- ----------
1 1 3
2 4 7
3 8 10

SELECT SUM of each row and the next row

Table three columns id, numers1 and numbers2. We need to summarize numers1 and numbers2 but the first row to the second row numers1 numers2 the second with the third and forth etc.:
CREATE TABLE tb1 (id INTEGER PRIMARY KEY AUTOINCREMENT,numbers1,numbers2);
INSERT INTO tb1 (numbers1,numbers2) values(1,10);
INSERT INTO tb1 (numbers1,numbers2) values(2,20);
INSERT INTO tb1 (numbers1,numbers2) values(3,30);
INSERT INTO tb1 (numbers1,numbers2) values(4,40);
INSERT INTO tb1 (numbers1,numbers2) values(5,50);
I want to get as:
21
32
43
54
with the reference of getting the correct row index per record here:
How to use ROW_NUMBER in sqlite
I was able to create the required result with the following query:
SELECT
num1 + coalesce(b_num2, 0)
FROM(
SELECT
num1,
(select count(*) from test as b where a.id >= b.id) as cnt
FROM test as a) as a
LEFT JOIN
(SELECT num2 as b_num2,
(select count(*) from test as b where a.id >= b.id) as cnt
FROM test as a
) as b
ON b.cnt = a.cnt + 1
Explanation:
by joining two same table of similar record index, then merge the next record with the current record and then sum num1 of current record with num2 of next record, I do not know how you want to deal with the last row as it does not have a next row so I assume it to add nothing to have a result of just the value of num1
Result:
For one row with a specific ID x, you can get values from the next row by searching for ID values larger than x, and taking the first such row:
SELECT ...
FROM tb1
WHERE id > x
ORDER BY id
LIMIT 1;
You can then use this as a correlated subquery to get that value for each row:
SELECT numbers1 + (SELECT T2.numbers2
FROM tb1 AS T2
WHERE T2.id > T1.id
ORDER BY T2.id
LIMIT 1) AS sum
FROM tb1 AS T1
WHERE sum IS NOT NULL; -- this omits the last row, where the subquery returns NULL

Assigning the rownnum values in a column in the table in ORACLE database?

Example:
It does not work.
UPDATE column_name SET rownum FROM table_name
This work!
UPDATE table_name SET column_name = rownum;
This works but the update is performed incorrectly
SELECT * FROM table_name ORDER BY column_name;
UPDATE table_name SET column_name = rownum;
I wish the following update behavior:
Note:'rownum ' It is not a physical column of the table
/*
pc_comentario = tableName
cod_comentario = columnName (Reference column for sorting)
dtc_andamento = columnDay (Reference column to update the "columnName" according to the order of this column)
*/
rownum | columnName | columnDay
1 1 day 1
2 5 day 5
3 7 day 2
After change with update
rownum | columnName (Update this column) | columnDay (sort by this column)
1 1 day 1
2 2 day 2
3 3 day 5
ALMOST DONE! this column 'cod_comentario_1 "which was materialized in RAM is correct. I need this column" cod_comentario_1 "that does not exist in the table is acknowledged in the consultations with java.
SELECT cod_comentario, dtc_andamento, cod_processo ,
ROW_NUMBER()
OVER (PARTITION BY cod_processo
ORDER BY dtc_andamento) cod_comentario_1
FROM pc_comentario
upadate do not work this way:
UPDATE (
SELECT cod_processo
ROW_NUMBER()
OVER (PARTITION BY cod_processo
ORDER BY dtc_andamento)cod_comentario_1
FROM pc_comentario
) SET cod_comentario_1)
order by Seq
I must enter the values of this consultation in a new column that I created
SELECT
ROW_NUMBER()
OVER (PARTITION BY cod_processo
ORDER BY dtc_andamento DESC)
FROM pc_comentario
Try:
UPDATE table_name
SET column_name = rownum
Shouldn't it be like below rather; I believe UPDATE statement has no FROM clause
UPDATE table_name SET column_name = rownum;
Again, it will work only if rownum is an existing column in your table. If you are trying to use Oracle rownum instead then consider using row_number() function rather
update table_name set column_name =
select rn from ( select column_name, row_number() over (order by column_name) rn
from table_name ) xx;
As you state yourself, rownum is a virtual column. It assigns a sequential value to each row of a particular result set. Which means that the row number of a row could be completely different in the result set of a different query.
If you really want to show the row number as part of the result set, specify it as you would any column:
select rownum as columnName, columnDay
from table
order by ...;

how update the second row in oracle11g?

I tried this request:
UPDATE studentTble e SET e.oStudent.oPerson.oAddr.city='UK' WHERE rownum = 2
ID NAME STREET CITY
100 --------Henrry.Student-----ST 17.---NY
101 --------Samm.Student-------ST 17D.--OR
102 --------Hanna.Student------ST 25D.--MX
WHERE rownum = 2
That is not how ROWNUM works. Rownum is not incremented to 2 unless Oracle assigns rownum to the first row. So, WHERE ROWNUM = 2 would return no rows, since rownum is never incremented beyond 1 in this case.
how update the second row in oracle11g?
There is nothing called a Nth row unless you have an ordered set of rows. In your case, if you have an explicit ORDER BY on ID column, by default in ascending order, then you could choose the second row from the sub-query.
UPDATE studenttble e
SET e.ostudent.operson.oaddr.city = 'UK'
WHERE id = (SELECT id
FROM (SELECT id,
ROWNUM rn
FROM (SELECT id,
ROWNUM rn
FROM studenttble
ORDER BY id))
WHERE rn = 2)
You could also use ANALYTIC ROW_NUMBER() to assign rank to each row ordered by ID column.

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