Select query INNER JOIN issue - sql

Question

I have tow tables Requisitions and RequisitionDetails
Requisitions table
+---------------+-----------------+
| RequisitionID | RequisitionDate |
+---------------+-----------------+
| 1 | 2016-08-17 |
| 2 | 2016-08-18 |
| 3 | 2016-08-19 |
+---------------+-----------------+
RequisitionDetails table
+---------------------+---------------+--------+----------+------------------+
| RequisitionDetailID | RequisitionID | ItemID | Quantity | ReceivedQuantity |
+---------------------+---------------+--------+----------+------------------+
| 1 | 1 | 1 | 2 | 1 |
| 2 | 1 | 2 | 3 | 2 |
| 3 | 2 | 3 | 4 | 3 |
+---------------------+---------------+--------+----------+------------------+
I am trying to get Requisition data where Quantity is not equal to ReceivedQuantity.
i have tried the below query but its record with RequisitionID 1 twice.
How can i make the query returns the Requisition data without repeating the requisition data based on items that have Quantity is not equal to ReceivedQuantity.
SELECT
dbo.Requisitions.RequisitionID,
dbo.Requisitions.RequisitionDate
FROM dbo.Requisitions
INNER JOIN dbo.RequisitionDetails
ON dbo.Requisitions.RequisitionID = dbo.RequisitionDetails.RequisitionID
where dbo.RequisitionDetails.Quantity != dbo.RequisitionDetails.ReceivedQuantity

Answer 1

It's returning twice because of the two rows with RequistionID = 1 in the RequistionDetails table. Since the rows returned are exact duplicates you can simply add the DISTINCT keyword to your select to see one of them:
SELECT DISTINCT
dbo.Requisitions.RequisitionID,
dbo.Requisitions.RequisitionDate
FROM dbo.Requisitions
INNER JOIN dbo.RequisitionDetails
ON dbo.Requisitions.RequisitionID = dbo.RequisitionDetails.RequisitionID
where dbo.RequisitionDetails.Quantity!=
dbo.RequisitionDetails.ReceivedQuantity
You should also use some aliases to clean up your query:
SELECT DISTINCT
R.RequisitionID,
R.RequisitionDate
FROM dbo.Requisitions R
INNER JOIN dbo.RequisitionDetails RD ON R.RequisitionID = RD.RequisitionID
WHERE RD.Quantity != RD.ReceivedQuantity

Answer 2

You also can use exists for your case
select
* from requistions rq where exists(
select 1 from RequisitionDetails rd where rd.RequisitionID=rq.RequisitionID
and rd.Quantity!=rd.ReceivedQuantity)

Answer 3

As you don't need columns from the 2nd table you can also switch to EXISTS to avoid DISTINCT:
SELECT req.*
FROM dbo.Requisitions as req
WHERE EXISTS
( SELECT * FROM dbo.RequisitionDetails as req_det
WHERE req.RequisitionID = req_det.RequisitionID
AND Quantity <> ReceivedQuantity
)
Or IN:
SELECT req.*
FROM dbo.Requisitions
WHERE RequisitionID IN
( SELECT RequisitionID
FROM dbo.RequisitionDetails
WHERE Quantity <> ReceivedQuantity
)