How to auto generate number between 10000 to 99999 without repeat number

From your question its not clear that where you want this means in code behind or database query.

if want in code-behind try this:-

Random number = new Random();

int genNumber = number.nextInt();

while (true)
 {
    genNumber = number.nextInt();
    if (genNumber > 10000 && genNumber < 99999)
                    {
        break;
      }
}
System.out.println("Random  Number:"+genNumber);

sql query:-

SELECT FLOOR(RAND() * 99999) AS random_num
FROM table_Name
WHERE "col_Name" NOT IN (SELECT my_number FROM numbers_mst)
LIMIT 1

Why just not use standard Random.Next Method (Int32, Int32)[^]?

Random rand = new Random();
int value = rand.Next(10000, 100000);

In case you are generating random numbers in loop, you need to create instance of Random outside the loop (class static readonly field would be good for this).

In SQL Server you can use this code for getting single random number:

SELECT 10000 + CAST(RAND() * (100000 - 10000) AS INT)

In case you need to generate random number for each row of your result set, you have to use NEWID[^] instead of RAND[^] function:

SELECT 10000 + (ABS(CAST(CAST(NEWID() AS VARBINARY) AS INT)) % (100000 - 10000))