RAND (Transact-SQL)

Applies to: SQL Server Azure SQL Database Azure SQL Managed Instance Azure Synapse Analytics

Returns a pseudo-random float value from 0 through 1, exclusive.

Transact-SQL syntax conventions

RAND ( [ seed ] )

An integer expression (tinyint, smallint, or int) that gives the seed value. If seed isn't specified, the SQL Server Database Engine assigns a seed value at random. For a specified seed value, the result returned is always the same.

float

Repetitive calls of RAND() with the same seed value return the same results.

• For one connection, if RAND() is called with a specified seed value, all subsequent calls of RAND() produce results based on the seeded RAND() call. For example, the following query always returns the same sequence of numbers.

  SELECT RAND(100),
          RAND(),
          RAND();
  

• When you use the RAND() function in an UPDATE or INSERT query, all affected rows get the same value.

The following example produces four different random numbers generated by the RAND() function.

DECLARE @counter AS SMALLINT;

SET @counter = 1;

WHILE @counter < 5
    BEGIN
        SELECT RAND() AS RandomNumber;
        SET @counter = @counter + 1;
    END
GO

The following example uses the ROUND() function to randomly return either 0 or 1.

SELECT ROUND(RAND(), 0) AS ZeroOrOne;
GO

You can scale the range of the random float by multiplying the RAND() function with an integer value. The following example returns a random float between 0 and 10.

DECLARE @Constant AS INT;
SET @Constant = 10;

SELECT @Constant * RAND() AS RandomNumber;
GO

You can generate a random integer value by scaling the RAND() function and combining it with the ROUND(), FLOOR(), or CEILING() functions. The following example returns a random integer between 0 and 10, inclusive.

DECLARE @Constant AS INT;
SET @Constant = 10;

SELECT ROUND(@Constant * RAND(), 0) AS FirstRandomInteger,
       FLOOR(@Constant * RAND()) AS SecondRandomInteger,
       CEILING(@Constant * RAND()) AS ThirdRandomInteger;
GO

The following example populates a table variable with random int, float, and bit values.

DECLARE @RandomTable TABLE (
    RandomIntegers INT,
    RandomFloats FLOAT,
    RandomBits BIT);

DECLARE @RowCount AS INT;
DECLARE @Counter AS INT;

SET @RowCount = 10;
SET @Counter = 1;

WHILE @Counter <= @RowCount
    BEGIN
        INSERT INTO @RandomTable
        VALUES (ROUND(10 * RAND(), 0), RAND(), CAST (ROUND(RAND(), 0) AS BIT));
        SET @Counter = @Counter + 1;
    END

SELECT *
FROM @RandomTable;
GO

• Mathematical functions (Transact-SQL)