MSSQL - The random number generator with a random initialization (random seed)

The random number generator function RAND() produces every time the same sequence of random numbers from 0.0000 to 1.0000.

You can initiate it with some number (seed value) and then RAND(SeedValue) will return a different sequence.
But for the same initialization value RAND() will generate the same sequence of random numbers.
To get a different sequence every time we need each time a different initialization value.
To do this, we can use a combination of NEWID() and CHECKSUM():

SELECT RND=RAND(CHECKSUM(NEWID()));

For example:

SELECT RND=RAND(CHECKSUM(NEWID())) FROM MyBigTable;

MSSQL - How to get rows in random sort order

Sometimes it is necessary to get the query result sorted in random order.

The first idea is to use a random number generator:

SELECT * FROM MyTable ORDER BY RAND();

But if we run this query several times, we can see that the rows are returned each time in the same order.
There is another function that returns something random - NEWID().
This function creates a unique value of type uniqueidentifier (GUID).

SELECT * FROM MyTable ORDER BY NEWID();

If you need to return a set of 100 random rows (Table Sample), you can do following:

SELECT TOP(100) * FROM MyTable ORDER BY NEWID();