QL Server has a built-in function that generates a random number, the RAND()
mathematical function. The RAND math function returns a random float
value from 0 through 1. It can take an optional seed parameter, which is
an integer expression (tinyint, smallint or int) that gives the seed or start
value.
To use it, you can simply do a simple SELECT, as follows:
The Downside of the RAND Function
One thing to take note with the RAND function is that if the seed parameter is
passed to it, the output will always be the same. This can be seen with
the following:
To use it, you can simply do a simple SELECT, as follows:
SELECT RAND() AS [RandomNumber]The result generated by this SELECT statement is as follows (note that your results may be different from the value shown here, hence the name random)
RandomNumber --------------------- 0.34344339282376501The output of the RAND function will always be a value between 0 and 1. If you want to generate a random integer number, all you have to do is multiply it by the maximum value you want generated and then get rid of the decimal places. One way of getting rid of the decimal places is by CASTing it to INT. Here's an example of generating a random number with a maximum value of 999,999:
SELECT CAST(RAND() * 1000000 AS INT) AS [RandomNumber]And here's an example result of this SELECT statement:
RandomNumber ------------ 163819
The Downside of the RAND Function
SELECT RAND(1) AS [RandomNumber]Running this SELECT statement multiple times with 1 as the seed of the RAND function will always yield the same result:
RandomNumber --------------------- 0.71359199321292355Another thing to take note with the RAND function is that if it is included in a SELECT statement on a table, the value returned for each row will be the same, as can be seen with the following example.
SELECT TOP 10 RAND() AS [RandomNumber], [CustomerID], [CompanyName], [ContactName] FROM [dbo].[Customers]
RandomNumber CustomerID CompanyName ContactName -------------------- ---------- ----------------------------------- ------------------- 0.21090395019612362 ALFKI Alfreds Futterkiste Maria Anders 0.21090395019612362 ANATR Ana Trujillo Emparedados y helados Ana Trujillo 0.21090395019612362 ANTON Antonio Moreno Taquería Antonio Moreno 0.21090395019612362 AROUT Around the Horn Thomas Hardy 0.21090395019612362 BERGS Berglunds snabbköp Christina Berglund 0.21090395019612362 BLAUS Blauer See Delikatessen Hanna Moos 0.21090395019612362 BLONP Blondesddsl père et fils Frédérique Citeaux 0.21090395019612362 BOLID Bólido Comidas preparadas Martín Sommer 0.21090395019612362 BONAP Bon app' Laurence Lebihan 0.21090395019612362 BOTTM Bottom-Dollar Markets Elizabeth Lincoln
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