I'm trying to populate 3 columns all rows with some random ints.
The code below has an error
Incorrect syntax near "#Upper. Expecting ( or Select
What am I doing wrong?
---- Create the variables for the random number generation
DECLARE #Random INT;
DECLARE #Upper INT;
DECLARE #Lower INT
---- Create a random number between 1 and 111
SET #Lower = 1 -- The lowest random number
SET #Upper = 111 -- The highest random number
UPDATE [tblProject]
SET
[ContractorID1] = #Random = ROUND(((#Upper - #Lower -1) * RAND() + #Lower), 0) -- error
,[ContractorID2] = #Random = ROUND(((#Upper - #Lower -1) * RAND() + #Lower), 0) -- error
,[ContractorID3] = #Random = ROUND(((#Upper - #Lower -1) * RAND() + #Lower), 0) -- error
Take out the "#Random = " in your update statement. It doesn't serve any purpose. You aren't using that variable at all, so you have no need to even declare it. Just do direct assignment.
And as you've discovered, the RAND() function will return the same value for the same row. If you need something different, there are other solutions.
I use following sql query to update MyTable. the code take between 5 to 15 min. to update MyTabel as long as ROWS <= 100000000 but when Rows > 100000000 it take exponential time to update MYTable. How can I change this code to use set-base instead of while loop?
DECLARE #startTime DATETIME
DECLARE #batchSize INT
DECLARE #iterationCount INT
DECLARE #i INT
DECLARE #from INT
DECLARE #to INT
SET #batchSize = 10000
SET #i = 0
SELECT #iterationCount = COUNT(*) / #batchSize
FROM MyTable
WHERE LitraID = 8175
AND id BETWEEN 100000000 AND 300000000
WHILE #i <= #iterationCount BEGIN
BEGIN TRANSACTION T
SET #startTime = GETDATE()
SET #from = #i * #batchSize
SET #to = (#i + 1) * #batchSize - 1
;WITH data
AS (
SELECT DoorsReleased, ROW_NUMBER() OVER (ORDER BY id) AS Row
FROM MyTable
WHERE LitraID = 8175
AND id BETWEEN 100000000 AND 300000000
)
UPDATE data
SET DoorsReleased = ~DoorsReleased
WHERE row BETWEEN #from AND #to
SET #i = #i + 1
COMMIT TRANSACTION T
END
One of your issues is that your select statement in the loop fetches all records for LitraID = 8175, sets row numbers, then filters in the update statement. This happens on every iteration.
One way round this would be to get all ids for the update before entering the loop and storing them in a temporary table. Then you can write a similar query to the one you have, but joining to this table of ids.
However, there is an even easier way if you know approximately how many records have LitraID = 8175 and if they are spread throughout the table, not bunched together with similar ids.
DECLARE #batchSize INT
DECLARE #minId INT
DECLARE #maxId INT
SET #batchSize = 10000 --adjust according to how frequently LitraID = 8175, larger numbers if infrequent
SET #minId = 100000000
WHILE #minId <= 300000000 BEGIN
SET #maxId = #minId + #batchSize - 1
IF #maxId > 300000000 BEGIN
SET #maxId = 300000000
END
BEGIN TRANSACTION T
UPDATE MyTable
SET DoorsReleased = ~DoorsReleased
WHERE id BETWEEN #minId AND #maxId
COMMIT TRANSACTION T
SET #minId = #maxId + 1
END
This will use the value of id to control the loop, meaning you don't need the extra step to calculate #iterationCount. It uses small batches so that the table isn't locked for long periods. It doesn't have any unnecessary SELECT statements and the WHERE clause in the update is efficient assuming id has an index.
It won't have exactly the same number of records updated in every transaction, but there's no reason it needs to.
This will eliminate the loop
UPDATE MyTable
set DoorsReleased = ~DoorsReleased
WHERE LitraID = 8175
AND id BETWEEN 100000000 AND 300000000
AND DoorsReleased is not null -- if DoorsReleased is nullable
-- AND DoorsReleased <> ~DoorsReleased</strike>
if you are set on looping
below will NOT work
I thought ~ was part of the column name but it is a not operator
select 1;
WHILE (##ROWCOUNT > 0)
BEGIN
UPDATE top (100000) MyTable
set DoorsReleased = ~DoorsReleased
WHERE LitraID = 8175
AND id BETWEEN 100000000 AND 300000000
AND ( DoorsReleased <> ~DoorsReleased
or ( DoorsReleased is null and ~DoorsReleased is not null )
)
END
Inside a transaction I don't think looping would have value as the transaction log cannot clear. And a batch size of 10,000 is small.\
as stated in a comment if you want to loop then try using id as row_number() all those loops is expensive
you might be able to use OFFSET
I want to select nth record randomly from 100 of records by using select query in SQL Server
Here is a one-query solution:
select top 1 t.*
from table t
order by newid();
In the below code #R produces the random number and it is used by the CTE to pick the random row.
DECLARE #Upper INT;
DECLARE #Lower INT;
SET #Lower = 1
SET #Upper = 100
DECLARE #R INT = (SELECT #Lower + CONVERT(INT, (#Upper-#Lower+1)*RAND()))
;WITH myTableWithRows AS (
SELECT (ROW_NUMBER() OVER (ORDER BY myTable.SomeField)) as row,*
FROM myTable)
SELECT * FROM myTableWithRows WHERE row = #R
How to create random number for an ID field In SQL Server?
I want to create random number betwen 1000 to 9999.
How to create this structure?
RAND is a built in function. It should meet your needs. This should give you the desired results: select cast(rand() * 8999 + 1000 as int)
http://msdn.microsoft.com/en-us/library/ms177610%28v=SQL.105%29.aspx
You've not mention whether you want random number generated as unique non-repetitive.
DECLARE #Random INT;
DECLARE #Upper INT;
DECLARE #Lower INT;
---- This will create a random number between 1 and 999
SET #Lower = 1000 ---- The lowest random number
SET #Upper = 9999 ---- The highest random number
SELECT #Random = ROUND(((#Upper - #Lower -1) * RAND() + #Lower), 0)
SELECT #Random;
Source
Another method
select number/power(10,len(number)-4) as number from
(
select top 10000 abs(checksum(newid())) as number
from sysobjects s1 cross join sysobjects s2
) as T
Also refer this http://beyondrelational.com/modules/2/blogs/70/posts/10810/generating-random-numbers-part-ii.aspx
Is it possible in Microsoft SQL Server generate random int value from Min to Max (3-9 example, 15-99 e.t.c)
I know, I can generate from 0 to Max, but how to increase Min border?
This query generate random value from 1 to 6. Need to change it from 3 to 6.
SELECT table_name, 1.0 + floor(6 * RAND(convert(varbinary, newid()))) magic_number
FROM information_schema.tables
Added 5 sec later:
SELECT table_name, 3.0 + floor(4 * RAND(convert(varbinary, newid()))) magic_number
FROM information_schema.tables
A helpful editor added the 'Select' before each statement but the point of this item is that it can generate unique keys for each row in a return, not just one item (For that I would us the Rand() function).
For example:
Select top 100 Rand(),* from tblExample
Would return the same random value for all 100 rows.
While:
Select top 100 ABS(CHECKSUM(NEWID()) % 10),* from tblexample
Would return a different random value between 0 and 9 on each row in the return.
So while the select makes it easier to copy and paste, you can copy the logic into a select statement if that is what is required.
This generates a random number between 0-9
SELECT ABS(CHECKSUM(NEWID()) % 10)
1 through 6
SELECT ABS(CHECKSUM(NEWID()) % 6) + 1
3 through 6
SELECT ABS(CHECKSUM(NEWID()) % 4) + 3
Dynamic (Based on Eilert Hjelmeseths Comment - thanks to jiraiya for providing the visual presentation)
SELECT ABS(CHECKSUM(NEWID()) % (#max - #min + 1)) + #min
Updated based on comments:
NEWID generates random string (for each row in return)
CHECKSUM takes value of string and creates number
modulus (%) divides by that number and returns the remainder (meaning max value is one less than the number you use)
ABS changes negative results to positive
then add one to the result to eliminate 0 results (to simulate a dice roll)
I see you have added an answer to your question in SQL Server 2008 you can also do
SELECT 3 + CRYPT_GEN_RANDOM(1) % 4 /*Random number between 3 and 6*/
FROM ...
A couple of disadvantages of this method are
This is slower than the NEWID() method
Even though it is evaluated once per row the query optimiser does not realise this which can lead to odd results.
but just thought I'd add it as another option.
You can do this:
DECLARE #maxval TINYINT, #minval TINYINT
select #maxval=24,#minval=5
SELECT CAST(((#maxval + 1) - #minval) *
RAND(CHECKSUM(NEWID())) + #minval AS TINYINT)
And that was taken directly from this link, I don't really know how to give proper credit for this answer.
Here is the simple and single line of code
For this use the SQL Inbuild RAND() function.
Here is the formula to generate random number between two number (RETURN INT Range)
Here a is your First Number (Min) and b is the Second Number (Max) in Range
SELECT FLOOR(RAND()*(b-a)+a)
Note: You can use CAST or CONVERT function as well to get INT range number.
( CAST(RAND()*(25-10)+10 AS INT) )
Example:
SELECT FLOOR(RAND()*(25-10)+10);
Here is the formula to generate random number between two number (RETURN DECIMAL Range)
SELECT RAND()*(b-a)+a;
Example:
SELECT RAND()*(25-10)+10;
More details check this: https://www.techonthenet.com/sql_server/functions/rand.php
Simply:
DECLARE #MIN INT=3; --We define minimum value, it can be generated.
DECLARE #MAX INT=6; --We define maximum value, it can be generated.
SELECT #MIN+FLOOR((#MAX-#MIN+1)*RAND(CONVERT(VARBINARY,NEWID()))); --And then this T-SQL snippet generates an integer between minimum and maximum integer values.
You can change and edit this code for your needs.
Nice and simple, from Pinal Dave's site:
http://blog.sqlauthority.com/2007/04/29/sql-server-random-number-generator-script-sql-query/
DECLARE #Random INT;
DECLARE #Upper INT;
DECLARE #Lower INT
SET #Lower = 3 ---- The lowest random number
SET #Upper = 7 ---- One more than the highest random number
SELECT #Random = ROUND(((#Upper - #Lower -1) * RAND() + #Lower), 0)
SELECT #Random
(I did make a slight change to the #Upper- to include the upper number, added 1.)
In general:
select rand()*(#upper-#lower)+#lower;
For your question:
select rand()*(6-3)+3;
<=>
select rand()*3+3;
SELECT ROUND((6 - 3 * RAND()), 0)
Lamak's answer as a function:
-- Create RANDBETWEEN function
-- Usage: SELECT dbo.RANDBETWEEN(0,9,RAND(CHECKSUM(NEWID())))
CREATE FUNCTION dbo.RANDBETWEEN(#minval TINYINT, #maxval TINYINT, #random NUMERIC(18,10))
RETURNS TINYINT
AS
BEGIN
RETURN (SELECT CAST(((#maxval + 1) - #minval) * #random + #minval AS TINYINT))
END
GO
DECLARE #min INT = 3;
DECLARE #max INT = 6;
SELECT #min + ROUND(RAND() * (#max - #min), 0);
Step by step
DECLARE #min INT = 3;
DECLARE #max INT = 6;
DECLARE #rand DECIMAL(19,4) = RAND();
DECLARE #difference INT = #max - #min;
DECLARE #chunk INT = ROUND(#rand * #difference, 0);
DECLARE #result INT = #min + #chunk;
SELECT #result;
Note that a user-defined function thus not allow the use of RAND(). A workaround for this (source: http://blog.sqlauthority.com/2012/11/20/sql-server-using-rand-in-user-defined-functions-udf/) is to create a view first.
CREATE VIEW [dbo].[vw_RandomSeed]
AS
SELECT RAND() AS seed
and then create the random function
CREATE FUNCTION udf_RandomNumberBetween
(
#min INT,
#max INT
)
RETURNS INT
AS
BEGIN
RETURN #min + ROUND((SELECT TOP 1 seed FROM vw_RandomSeed) * (#max - #min), 0);
END