Question

I have two tables as following.

‘Areas’ Table

|    AreaKey      |    AreaID    |
|-----------------|--------------|
| <identity/int>  |  <varchar>   |

‘Readings’ Table

|    ReadingKey   |      AreaKey      |   Reading   |    ReadingDateTime   |
|-----------------|-------------------|-------------|----------------------|
| <identity/int>  |<FK:AreaKey-Areas> |   <float>   |      <datetime>      |

• ‘AreaKey’ in Readings table is a foreign key to ‘AreaKey’ of Areas table.

Areas table already have some data with row id’s ranging from 1 to 50.

I want to populate the Readings table with some sample data – (random float values for ‘Reading’ column between 1.0 and 100.0 AND a random datetime value for ReadingDateTime between a given DateTime range; for example between current datetime and a datetime 3 months back). These values should be inserted to the Reading table by randomly selecting AreaKeys which already exist in the Areas table.

In other words I want to insert random reading values to randomly selected areas, with random datetimes.

Can anyone give me a clue on how to do this?

Answer 1

Assuming your Areas table has 50 records, with row ids 1-50, I would just look into using the RAND function.

Something like this seems to work:

SELECT ROUND(((50 - 1 -1) * RAND() + 1), 0) as AreakKey,
    ROUND(((100 - 1 -1) * RAND() + 1), 1) as Reading,
    DATEADD(mm,-3,GETDATE()) +
(
ABS(
    CAST(
        CAST( NewID() AS BINARY(8) ) AS INT
    )
)
%
CAST(
    (GETDATE() - DATEADD(mm,-3,GETDATE())) AS INT
    )
) as ReadingDateTime   

And here’s some SQL Fiddle.

Good luck.