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07-31-2023, 07:36 AM
SELECT Orders.OrderNumber, LineItems.Quantity, LineItems.Description
FROM Orders
JOIN LineItems
ON LineItems.LineItemGUID =
(
SELECT TOP 1 LineItemGUID
FROM LineItems
WHERE OrderID = Orders.OrderID
)
In SQL Server 2005 and above, you could just replace `INNER JOIN` with `CROSS APPLY`:
SELECT Orders.OrderNumber, LineItems2.Quantity, LineItems2.Description
FROM Orders
CROSS APPLY
(
SELECT TOP 1 LineItems.Quantity, LineItems.Description
FROM LineItems
WHERE LineItems.OrderID = Orders.OrderID
) LineItems2
Please note that `TOP 1` without `ORDER BY` is not deterministic: this query you will get you one line item per order, but it is not defined which one will it be.
Multiple invocations of the query can give you different line items for the same order, even if the underlying did not change.
If you want deterministic order, you should add an `ORDER BY` clause to the innermost query.
[Example sqlfiddle](
FROM Orders
JOIN LineItems
ON LineItems.LineItemGUID =
(
SELECT TOP 1 LineItemGUID
FROM LineItems
WHERE OrderID = Orders.OrderID
)
In SQL Server 2005 and above, you could just replace `INNER JOIN` with `CROSS APPLY`:
SELECT Orders.OrderNumber, LineItems2.Quantity, LineItems2.Description
FROM Orders
CROSS APPLY
(
SELECT TOP 1 LineItems.Quantity, LineItems.Description
FROM LineItems
WHERE LineItems.OrderID = Orders.OrderID
) LineItems2
Please note that `TOP 1` without `ORDER BY` is not deterministic: this query you will get you one line item per order, but it is not defined which one will it be.
Multiple invocations of the query can give you different line items for the same order, even if the underlying did not change.
If you want deterministic order, you should add an `ORDER BY` clause to the innermost query.
[Example sqlfiddle](
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)