SQL generate integers without using loops - mysql

Is there any way to create a table with column containing integer from 0 to 1000 without using loops?
Regards,
KC


You can use a recursive CTE:
with recursive n as (
select 1 as n
union all
select n + 1
from n
where n < 1000
)
select n
from n;


CROSS JOIN will be faster than a recursive CTE (kudos to Itzik Ben-Gan)
WITH
L0 AS ( SELECT 1 AS c
FROM (VALUES(1),(1),(1),(1),(1),(1),(1),(1),(1),(1)) AS D(c) ),
L1 AS ( SELECT 1 AS c FROM L0 AS A CROSS JOIN L0 AS B ),
L2 AS ( SELECT 1 AS c FROM L1 AS A CROSS JOIN L1 AS B ),
Nums AS ( SELECT ROW_NUMBER() OVER(ORDER BY (SELECT NULL)) AS rownum
FROM L2 )
SELECT rownum - 1 AS n
FROM Nums
ORDER BY rownum
LIMIT 1000;


Schema (MySQL v8.0)
Query #1
with recursive numbers(id) as (
select 0 as id
union all
select id+1 from numbers where id < 999
)
select id from numbers;
id
0
1
2
3
4
5
6
.
.
.
997
998
999
View on DB Fiddle

Related

How to get all missing numbers from id column

Users table has id field in mysql database, and table has below record in id field
|id|
2
3
5
6
9
10
15
16
18
21
25
I want to get missing records row like below:-
1
4
7
8
11
12
13
14
17
19
20
22
23
24

How cool is this ?
SELECT seq.`id` FROM (
SELECT #row := #row + 1 as `id`
FROM `users` t, (SELECT #row := 0) r
CROSS JOIN `users` t2
) as seq WHERE seq.`id` NOT IN (SELECT `id` FROM `users`)
AND seq.`id` <= (SELECT max(`id`) from `users`);
If you want the missing ids for analytical purpose, should love this one:
SELECT CONCAT(dt.missing, IF(dt.`found`-1 > dt.missing, CONCAT(' to ', dt.`found` - 1), '')) AS missing
FROM ( SELECT #rownum:=#rownum+1 AS `missing`,
IF (#rownum=id, 0, #rownum:=id) AS `found`
FROM ( SELECT #rownum:=0 ) AS r
JOIN users
ORDER BY id ) AS dt
WHERE dt.`found`!= 0;

Use a calendar table approach and anti-join approach:
CREATE TABLE nums (id INT);
INSERT INTO nums (id)
(
SELECT (t*10+u+1) x FROM
(SELECT 0 t UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION
SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9) A,
(SELECT 0 u UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION
SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9) B
);
SELECT
n.id
FROM nums n
LEFT JOIN users u
ON n.id = u.id
WHERE
u.id IS NULL
ORDER BY
n.id;
Demo
Note that in the demo and query I did not limit the height of the range of missing numbers which gets returned. I arbitrarily used a sequence of numbers 1..100, but you may restrict to any size you want.

SQL query to find new column

I need your help. I have a table named Test_Result with 2 columns as shown below.
ID Source_ID
10 1
20 2
30 2
40 3
50 3
60 3
70 4
I am trying to get output as below,but unable to get logic.
ID Parent_ID Source_ID
10 Null 1
20 Null 2
30 20 2
40 Null 3
50 40 3
60 50 3
70 Null 4
Kindly help me with this scenario. I attached question in picture for as well.
Regards,
Abhi

These solutions (ROW_NUMBER/LAG) will work for MySQL 8.0+ or MariaDB 10.2
You could use ROW_NUMBER() and join to previous row:
CREATE TABLE tab(ID INT ,Source_ID INT);
INSERT INTO tab(id, Source_id)
SELECT 10, 1
UNION ALL SELECT 20 , 2
UNION ALL SELECT 30, 2
UNION ALL SELECT 40 , 3
UNION ALL SELECT 50 , 3
UNION ALL SELECT 60 , 3
UNION ALL SELECT 70 , 4;
WITH cte AS (
SELECT *, ROW_NUMBER() OVER(ORDER BY id) AS rn
FROM tab
)
SELECT c1.ID,
CASE WHEN c1.Source_ID = c2.Source_ID THEN c2.Id END AS Parent_Id,
c1.Source_ID
FROM cte c1
LEFT JOIN cte c2
ON c1.rn = c2.rn+1;
Rextester Demo
EDIT:
Using LAG() windowed function:
SELECT c1.ID,
CASE
WHEN c1.Source_ID = LAG(Source_ID) OVER w THEN LAG(ID) OVER w
END AS Parent_Id,
c1.Source_ID
FROM tab c1
WINDOW w AS (ORDER BY ID)
ORDER BY id;
DBFiddle
EDIT2:
Simulating LAG using variables:
SET #lag_Source_id='';
SET #lag_Id = '';
SELECT ID,
CASE WHEN Source_Id = lag_Source_ID THEN lag_ID END AS Parent_ID
,Source_ID
FROM (
SELECT ID
, Source_ID
, #lag_Source_id AS lag_Source_id
, #lag_Source_id:= Source_ID AS curr_Source_ID
, #lag_Id AS lag_ID
, #lag_Id := ID AS curr_ID
FROM tab
ORDER BY id
) AS sub
RextesterDemo2

if you are using mysql database simply do this,
SELECT ID, (ID + Source_ID) AS Parent_ID, Source_ID FROM tableName LIMIT 10;

Is it possible to get inverted result from existent data by user input?

Sorry for my title, I don't know how to describe it.
I have a table t1 as follow:
id t_id time
1 1 201501
2 1 201502
I want to get a recordset in a specify period like 201501, 201502, 201503, 201504, 201505, 201506, and the time not in t1. The specify period passed by user input.
I want the result like this:
id t_id time
1 1 201503
2 1 201504
3 1 201505
4 1 201506
Is it possible to get the result in one sql?
And I use php to collect user input.

SELECT a.*
FROM
(
SELECT 201501 user_input
UNION
SELECT 201502
UNION
SELECT 201503
UNION
SELECT 201504
UNION
SELECT 201505
UNION
SELECT 201506
) a
LEFT
JOIN t1 b
ON b.time = a.user_input
WHERE b.id IS NULL;

You could try something like this (sorry i have no Database here, so i can't test it): the trick is to select your values with UNION SELECT first.
SELECT v.x from (SELECT 201501 v
UNION SELECT 201502 v
UNION SELECT 201503 v
UNION SELECT 201504 v
UNION SELECT 201505 v
UNION SELECT 201506 v) x
WHERE v.x not in (SELECT time FROM t1)

(i) Create a table from existing one and (ii) display detailed data for which total is stored in table

From a table t1
product_id | quantity | total_amount
I want to create a table t2 with the columns
id | product_id | total_amount/quantity AS product_price
I want each record (t2.product_id, t2.product_price) to be shown t1.quantity times for the respective product:
1 | 400
1 | 400
1 | 400
2 | 75
2 | 75
Could you please tell me, how can I do this using bare SQL?

This seems to create the table, you are looking for:
CREATE TABLE T2 AS
SELECT
#rowid := #rowid + 1 AS id
, product_id
, total_amount / quantity AS product_price
FROM t1, (SELECT #rowid := 0) AS firstID
ORDER BY product_id
;
For the second part of your request, you could try:
SELECT
T.product_id
, T.total_amount / T.quantity AS price
FROM T1 T CROSS JOIN
(SELECT A.n + B.n * 10 + 1 n
FROM
(SELECT 0 AS n UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3
UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6
UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 9) A
, (SELECT 0 AS n UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3
UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6
UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 9) B
ORDER BY n
) N
WHERE N.n <= T.quantity
ORDER BY product_id
;
See it in action: SQL Fiddle.
Please comment if this requires adjustment / further detail.

How to INSERT INTO a range of numbers into a MYSQL table [duplicate]

How do I generate a range of consecutive numbers (one per line) from a MySQL query so that I can insert them into a table?
For example:
nr
1
2
3
4
5
I would like to use only MySQL for this (not PHP or other languages).

Here is one way to do it set-based without loops. This can also be made into a view for re-use. The example shows the generation of a sequence from 0 through 999, but of course, it may be modified to suit.
INSERT INTO
myTable
(
nr
)
SELECT
SEQ.SeqValue
FROM
(
SELECT
(HUNDREDS.SeqValue + TENS.SeqValue + ONES.SeqValue) SeqValue
FROM
(
SELECT 0 SeqValue
UNION ALL
SELECT 1 SeqValue
UNION ALL
SELECT 2 SeqValue
UNION ALL
SELECT 3 SeqValue
UNION ALL
SELECT 4 SeqValue
UNION ALL
SELECT 5 SeqValue
UNION ALL
SELECT 6 SeqValue
UNION ALL
SELECT 7 SeqValue
UNION ALL
SELECT 8 SeqValue
UNION ALL
SELECT 9 SeqValue
) ONES
CROSS JOIN
(
SELECT 0 SeqValue
UNION ALL
SELECT 10 SeqValue
UNION ALL
SELECT 20 SeqValue
UNION ALL
SELECT 30 SeqValue
UNION ALL
SELECT 40 SeqValue
UNION ALL
SELECT 50 SeqValue
UNION ALL
SELECT 60 SeqValue
UNION ALL
SELECT 70 SeqValue
UNION ALL
SELECT 80 SeqValue
UNION ALL
SELECT 90 SeqValue
) TENS
CROSS JOIN
(
SELECT 0 SeqValue
UNION ALL
SELECT 100 SeqValue
UNION ALL
SELECT 200 SeqValue
UNION ALL
SELECT 300 SeqValue
UNION ALL
SELECT 400 SeqValue
UNION ALL
SELECT 500 SeqValue
UNION ALL
SELECT 600 SeqValue
UNION ALL
SELECT 700 SeqValue
UNION ALL
SELECT 800 SeqValue
UNION ALL
SELECT 900 SeqValue
) HUNDREDS
) SEQ

Here's a hardware engineer's version of Pittsburgh DBA's solution:
SELECT
(TWO_1.SeqValue + TWO_2.SeqValue + TWO_4.SeqValue + TWO_8.SeqValue + TWO_16.SeqValue) SeqValue
FROM
(SELECT 0 SeqValue UNION ALL SELECT 1 SeqValue) TWO_1
CROSS JOIN (SELECT 0 SeqValue UNION ALL SELECT 2 SeqValue) TWO_2
CROSS JOIN (SELECT 0 SeqValue UNION ALL SELECT 4 SeqValue) TWO_4
CROSS JOIN (SELECT 0 SeqValue UNION ALL SELECT 8 SeqValue) TWO_8
CROSS JOIN (SELECT 0 SeqValue UNION ALL SELECT 16 SeqValue) TWO_16;

If you need the records in a table and you want to avoid concurrency issues, here's how to do it.
First you create a table in which to store your records
CREATE TABLE `incr` (
`Id` int(11) NOT NULL auto_increment,
PRIMARY KEY (`Id`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8;
Secondly create a stored procedure like this:
DELIMITER ;;
CREATE PROCEDURE dowhile()
BEGIN
DECLARE v1 INT DEFAULT 5;
WHILE v1 > 0 DO
INSERT incr VALUES (NULL);
SET v1 = v1 - 1;
END WHILE;
END;;
DELIMITER ;
Lastly call the SP:
CALL dowhile();
SELECT * FROM incr;
Result
Id
1
2
3
4
5

Let's say you want to insert numbers 1 through 100 into your table. As long as you have some other table that has at least that many rows (doesn't matter the content of the table), then this is my preferred method:
INSERT INTO pivot100
SELECT #ROW := #ROW + 1 AS ROW
FROM someOtherTable t
join (SELECT #ROW := 0) t2
LIMIT 100
;
Want a range that starts with something other than 1? Just change what #ROW gets set to on the join.

As you all understand, this is rather hacky so use with care
SELECT
id % 12 + 1 as one_to_twelve
FROM
any_large_table
GROUP BY
one_to_twelve
;

DECLARE i INT DEFAULT 0;
WHILE i < 6 DO
/* insert into table... */
SET i = i + 1;
END WHILE;

Very similar to the accepted response, but using the new WITH syntax for mysql >= 8.0 which makes a lot more legible and the intent is also clearer
WITH DIGITS (N) AS (
SELECT 0 UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL
SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL
SELECT 8 UNION ALL SELECT 9)
SELECT
UNITS.N + TENS.N*10 + HUNDREDS.N*100 + THOUSANDS.N*1000
FROM
DIGITS AS UNITS, DIGITS AS TENS, DIGITS AS HUNDREDS, DIGITS AS THOUSANDS;

In MariaDB you can do:
SELECT * FROM seq_i_to_N
For example:
SELECT * FROM seq_0_to_1000
SELECT * FROM seq_1_to_1000000
Reference: https://www.percona.com/blog/2020/07/27/generating-numeric-sequences-in-mysql/

The "shortest" way i know (in MySQL) to create a table with a long sequence is to (cross) join an existing table with itself. Since any (common) MySQL server has the information_schema.COLUMNS table i would use it:
DROP TABLE IF EXISTS seq;
CREATE TABLE seq (i MEDIUMINT AUTO_INCREMENT PRIMARY KEY)
SELECT NULL AS i
FROM information_schema.COLUMNS t1
JOIN information_schema.COLUMNS t2
JOIN information_schema.COLUMNS t3
LIMIT 100000; -- <- set your limit here
Usually one join should be enough to create over 1M rows - But one more join will not hurt :-) - Just don't forget to set a limit.
If you want to include 0, you should "remove" the AUTO_INCEMENT property.
ALTER TABLE seq ALTER i DROP DEFAULT;
ALTER TABLE seq MODIFY i MEDIUMINT;
Now you can insert 0
INSERT INTO seq (i) VALUES (0);
and negative numbers as well
INSERT INTO seq (i) SELECT -i FROM seq WHERE i <> 0;
You can validate the numbers with
SELECT MIN(i), MAX(i), COUNT(*) FROM seq;

All other answers are good, however they all have speed issues for larger ranges because they force MySQL to generate every number then filter them.
The following only makes MySQL generate the numbers that are needed, and therefore is faster:
set #amount = 55; # How many numbers from zero you want to generate
select `t0`.`i`+`t1`.`i`+`t2`.`i`+`t3`.`i` as `offset`
from
(select 0 `i` union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) `t0`,
(select 0 `i` union select 10 union select 20 union select 30 union select 40 union select 50 union select 60 union select 70 union select 80 union select 90) `t1`,
(select 0 `i` union select 100 union select 200 union select 300 union select 400 union select 500 union select 600 union select 700 union select 800 union select 900) `t2`,
(select 0 `i` union select 1000 union select 2000 union select 3000 union select 4000 union select 5000 union select 6000 union select 7000 union select 8000 union select 9000) `t3`
where `t3`.`i`<#amount
and `t2`.`i`<#amount
and `t1`.`i`<#amount
and `t0`.`i`+`t1`.`i`+`t2`.`i`+`t3`.`i`<#amount;
With the above you can generate upto 10,000 numbers (0 to 9,999) with no slower speed overhead for lower numbers, regardless how low they are.

Here's a way to do it with json_table if you have MySql 8 and above:
set #noRows = 100;
SELECT tt.rowid - 1 AS value
FROM JSON_TABLE(CONCAT('[{}', REPEAT(',{}', #noRows - 1), ']'),
"$[*]" COLUMNS(rowid FOR ORDINALITY)
) AS tt;
(h/t - https://www.percona.com/blog/2020/07/27/generating-numeric-sequences-in-mysql/)

The idea I want to share is not a precise response for the question but can be useful for some so I would like to share it.
If you frequently need only a limited set of numbers then it can be beneficial to create a table with the numbers you may need and just use that table every time. For example:
CREATE TABLE _numbers (num int);
INSERT _numbers VALUES (0), (1), (2), (3), ...;
This can be applied only if you need numbers below a certain reasonable limit, so don't use it for generating sequence 1...1 million but can be used for numbers 1...10k, for example.
If you have this list of numbers in the _numbers table then you can write queries like this, for obtaining the individual characters of a string:
SELECT number, substr(name, num, 1)
FROM users
JOIN _numbers ON num < length(name)
WHERE user_id = 1234
ORDER BY num;
If you need larger numbers than 10k then you can join the table to itself:
SELECT n1.num * 10000 + n2.num
FROM _numbers n1
JOIN _numbers n2
WHERE n1 < 100
ORDER BY n1.num * 10000 + n2.num; -- or just ORDER BY 1 meaning the first column

This is based on a previous answer (https://stackoverflow.com/a/53125278/2009581), but is compatible with MySQL 5.7. It works for replicas and read-only users:
SELECT x1.N + x10.N*10 + x100.N*100 + x1000.N*1000
FROM (SELECT 0 AS N UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 9) x1,
(SELECT 0 AS N UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 9) x10,
(SELECT 0 AS N UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 9) x100,
(SELECT 0 AS N UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 9) x1000
WHERE x1.N + x10.N*10 + x100.N*100 + x1000.N*1000 <= #max;
It generates integers in the range of [0, #max].

with recursive cte..
with recursive rnums as (
select 1 as n
union all
select n+1 as n from rnums
where n <10
)
select * from rnums
;
Result would be..
+------+
| n |
+------+
| 1 |
| 2 |
| 3 |
| 4 |
| 5 |
| 6 |
| 7 |
| 8 |
| 9 |
| 10 |
+------+
10 rows in set (0.00 sec)