Question

Based on Martin Smith’s answer here, I’ve been trying to use a very similar technique to creating 10000 random strings that start with two characters(A-Z), then two numbers(0-9) and then two characters(A-Z). Anybody know how to do this using the same technique or is it not possible, Thanks in advance
Paul

Answer 1

Slight modification to the original:

DECLARE @Numbers  TABLE
(
n INT PRIMARY KEY
);


WITH E00(N) AS (SELECT 1 UNION ALL SELECT 1),   --2
        E02(N) AS (SELECT 1 FROM E00 a, E00 b), --4
        E04(N) AS (SELECT 1 FROM E02 a, E02 b), --16
        E08(N) AS (SELECT 1 FROM E04 a, E04 b), --256
        E16(N) AS (SELECT 1 FROM E08 a, E08 b)  --65,536
INSERT INTO @Numbers
SELECT TOP 1000 ROW_NUMBER() OVER (ORDER BY (SELECT 0))
FROM E16

/* 
 1.  Build a table variable of numbers
 2.  For each row in the table (up to row 1000)
 3.  Get the top 2 numbers from the table variable
 4.  For each number, get the absolute value of the checksum of a GUID
 5.  This value will always be a positive integer
 6.  Get the remainder of that integer when divided by 26
 7.  This will always be a number between 0 and 25
 8.  If the absolute value number is divisible by 2, add 65 to the number (uppercase)
 9.  Otherwise, add 97 to the number (lowercase)
 10. Use that number as an ASCII value and get the character representation
 11. Use FOR XML PATH to convert the two characters in the subquery to a string
 12. Repeat the same logic for 2 numbers (use %9 to get two numbers between 0 and 9) 
 13. Repeat the same logic from previous steps to get two more alphabetic characters
*/

SELECT CAST((SELECT TOP 2 CHAR(CASE
                                  WHEN Abs(Checksum(Newid()))%2 = 0 THEN 65
                                  ELSE 97
                                END + Abs(Checksum(Newid()))%26)
             FROM   @Numbers n1
             WHERE  n1.n >= -n2.n 
             FOR XML PATH('')) AS CHAR(2)) + 
       CAST((SELECT TOP 2 Abs(Checksum(Newid()))%9
             FROM   @Numbers n1
             WHERE  n1.n >= -n2.n 
             FOR XML PATH('')) AS CHAR(2)) +             
       CAST((SELECT TOP 2 CHAR(CASE
                                  WHEN Abs(Checksum(Newid()))%2 = 0 THEN 65
                                  ELSE 97
                                END + Abs(Checksum(Newid()))%26)
             FROM   @Numbers n1
             WHERE  n1.n >= -n2.n /*So it gets re-evaluated for each row!*/
             FOR XML PATH('')) AS CHAR(2))
FROM   @Numbers n2