want to generate coupon code 5 digit number [duplicate] - sql-server

Question

This question already has answers here:
TSQL Generate 5 character length string, all digits [0-9] that doesn't already exist in database
(6 answers)
Closed 7 years ago.
i want to create a coupon code generator by using SQL database but i don't know how to generate 1000 of random number without repeating them. so can someone help me it's important. thanks

Answer 1

Records in a relational database tables are unordered by nature.
therefor, you can simply create a table that has all the values between #First and #Last (0 and 9999 in your case), and then use a random order by when selecting from that table. you can also use a simple int in the database table and just format it when you select the data from the table.
Since my main database is Sql server, and I have no experience with sqlite, I will use Sql Server syntax in my code example, and leave it up to you to find the sqllite equivalent.
First, create the table:
CREATE TABLE Tbl
(
IntValue int PRIMARY KEY,
IsUsed bit NOT NULL DEFAULT 0
)
Then, populate it with numbers between 0 and 9999:
;With CTE AS (
SELECT 0 As IntValue
UNION ALL
SELECT IntValue + 1
FROM CTE
WHERE IntValue + 1 < 10000
)
INSERT INTO Tbl (IntValue)
SELECT IntValue
FROM CTE
OPTION(MAXRECURSION 0)
Then, you want to select multiple values each time, so I would write a stored procedure like this:
CREATE PROCEDURE stp_GetCouponCodes
(
#Number int = 5 -- or whatever number is default
)
AS
BEGIN
DECLARE #UsedValues AS TABLE
(
IntValue int
)
BEGIN TRY
BEGIN TRANSACTION
INSERT INTO #UsedValues
SELECT TOP(#Number) IntValue
FROM Tbl
WHERE IsUsed = 0
ORDER BY NEWID()
UPDATE Tbl
SET IsUsed = 1
FROM Tbl
INNER JOIN
#UsedValues uv ON(Tbl.IntValue = uv.IntValue)
SELECT RIGHT('00000' + CAST(IntValue as varchar), 5)
FROM #UsedValues
COMMIT TRANSACTION
END TRY
BEGIN CATCH
IF ##TRANCOUNT > 0
ROLLBACK TRANSACTION
END CATCH
END
Then, when ever you want to generate coupons, simply execute the stored procedure with the number of coupons you want:
EXEC stp_GetCouponCodes 10;
See working fiddle example here.

Answer 2

The code below uses a quick method to generate 100 random 5-character strings based on the alphabet provided. You'll still need to perform duplicate checking, but this should get you started.
DECLARE #Quantity INT = 1000
DECLARE #Alphabet VARCHAR(100) = '0123456789'
DECLARE #Length INT = LEN(#Alphabet)
DECLARE #Top INT = SQRT(#Quantity) + 1
;WITH CTE AS (
SELECT TOP (#Top) *
FROM sys.objects
)
SELECT TOP (#Quantity)
SUBSTRING(#Alphabet, ABS(CHECKSUM(NEWID())) % #Length + 1, 1)
+ SUBSTRING(#Alphabet, ABS(CHECKSUM(NEWID())) % #Length + 1, 1)
+ SUBSTRING(#Alphabet, ABS(CHECKSUM(NEWID())) % #Length + 1, 1)
+ SUBSTRING(#Alphabet, ABS(CHECKSUM(NEWID())) % #Length + 1, 1)
+ SUBSTRING(#Alphabet, ABS(CHECKSUM(NEWID())) % #Length + 1, 1)
AS [Code]
FROM CTE X
CROSS JOIN CTE Y