Random Sampling

[Paul]

Hello. I have a table in Access that is updated each day with data
from the previous business day. The table consists of a date, name,
type and id. For this example, let's say that the types are Type A,
Type B or Type C. I need to take a random sampling of 10 id's for
each of the different Types for each Name that is listed for a
particular day. For example if 1 agent worked yesterday, I would
need to see a random sampling of 10 Type A id's, 10 Type B id's and 10
Type C id's for a grand total of 30. If more agents worked then I
would need to have the same for each of them.

Does this make sense? 10 random id numbers of each type for each
agent that worked on a particular day. Does anyone have any thoughts
on this?

Any help would be greatly appreciated.

Thanks

 

[ghetto_banjo]

One way to accomplish this, is to create a query that uses the Rnd()
function so that it sorts itself via a random number. Then you can
specify that it only returns the TOP 10 records per each Type.

I am assuming your id field is a primary key, preferably AutoNumber
type.

SELECT TOP 10 *
FROM YourTable
WHERE Type = "A"
ORDER BY Rnd(IsNull(ID)*0+1);


That would return 10 random Type A records I believe.

 

[Arvin Meyer [MVP]]

I'd do it with 3 queries, one for each type, then if necessary to combine
them, use a union query. So:

Create a function in a module:

Function GetRandNum(varValue As Variant) As Double
Randomize Timer
GetRandNum = Rnd(1)
End Function

The query would look like:

SELECT TOP 10 ID, [Name], [Date], Type
FROM YourTableName
WHERE Type = "A" ' or B or C
ORDER BY GetRandNum(ID);

Also, note that Name and Date are reserved words and you will have big
problems using them, which is why I used square brackets around them.

Now the Union query looks like:

Select * From Query A
UNION ALL
Select * From Query B
UNION ALL
Select * From Query C;