Find table with only two rows. Access 2016 - sql

Question

I'm looking for a query that I can use in MS Access 2016 which will give me all Company ID's that have the values "Iphone" and "Ipad". So all CompanyID that has only two rows with specific values.
CompanyID Product_Name
1 Iphone
1 Ipad
1 Headphones
2 Iphone
2 Galaxy
3 Playstation 4
3 Nintendo Switch
4 Iphone
4 Ipad
In the example table above I will therefore get the CompanyID = 4.
I have tried to use the same logic as in SQL from the this post but Access doesn't allow syntax USING.
The SQL query used in post is:
SELECT CompanyID
FROM DATA AS a
JOIN DATA AS b
USING (CompanyID)
WHERE a.Product_Name = "Iphone"
AND b.Product_Name = "Ipad";
Any feedback is much appreciated.

Answer 1

Since you state:
So all CompanyID that has only two rows with specific values... In the
example table above I will therefore get the CompanyID = 4.
It would seem that you require the CompanyID for which the only two Product_Name values are Ipad & Iphone, with no other values associated with the CompanyID.
To obtain this result, I might suggest the following SQL query:
select t.companyid
from data t
group by t.companyid
having max(t.product_name in ('Iphone','Ipad'))=-1
Which will return:
CompanyID
4
Here, for every record within each group of records associated with a given CompanyID, the expression t.product_name in ('Iphone','Ipad') is evaluated.
This expression will either return True (-1) or False (0).
If all records within the group are either 'Iphone' or 'Ipad', then this expression will return True (-1) for every record, and the maximum over the group will be -1.
Whereas, if any record within the group is some other value, this expression will return False (0) and therefore the maximum of the group will be 0, thus excluding it from the result.

Answer 2

You can use an INNER JOIN to filter the results that do not contain both values:
SELECT a.CompanyID
FROM (
SELECT CompanyID
FROM DATA
WHERE Product_Name = 'IPhone'
) a
INNER JOIN (
SELECT CompanyID
FROM DATA
WHERE Product_Name = 'Ipad'
) b ON b.CompanyID = a.CompanyID
Output:
CompanyID
1
4
How does this work?
Firstly all results that have an IPhone are gathered. Then this is joined with all results that have an IPad. Only results with both rows matching (because of the INNER JOIN) will be returned.

Answer 3

While late to this, it looks like they're only being pulled from one table - DATA. If that's the case then the easiest solution should just be
SELECT DATA.CompanyID
FROM (DATA)
WHERE DATA.Product_Name = "Iphone"
AND DATA.Product_Name = "Ipad";
For Access, the FROM statement is generally only used for combining tables, or queries, and the data manipulation is in the other statements.
If there's more than one table and the connection between the two tables is CompanyID, then it should look more like this;
SELECT DATA1.CompanyID
FROM (DATA1 INNER JOIN DATA1.CompanyID ON DATA2.CompanyID)
WHERE DATA2.Product_Name = "Iphone"
AND DATA2.Product_Name = "Ipad";