UNION Operator, or advice rewriting a query

[Laptopmini]

Language: Swift 3
Target: iOS 10.0
Pod Version: 0.11.0
xCode: 8.2.1

Hello,

I have in my database a table of items. I am trying to write a query which will let me know if a particular item is in the first "page" of items.

To do so, I need to query the table with a limit to get the first "page", so lets say:

var query = itemsTable.limit(10, offset: 0)

Next, I need to check if the item I am looking for is in this first page, so my initial reflex was to apply the following:

query = query.filter(ItemsTableExpressions.id == targetID)

However, since the execution is lazy and I have been just building an Expression (so to speak, since query is actually of type Table), this query will be optimized and result in the following:

SELECT * FROM itemsTable WHERE id = targetID LIMIT 10;

Which is not what I want. This gets all items matching the targetID and THEN limits those results to 10. My intuition was then to use UNION and just make 2 different queries and find their common result domain. However, as you may know, this library does not offer a UNION operator.

Now, I can obviously use raw SQL, but I'd like to keep it swifty, so to speak. Does anyone have advice on how to meet the result I need using this library (and probably without the use of UNION)?

[Laptopmini]

I figured out an alternative.

I declare my query, like I did:

var query = itemsTable.limit(10, offset: 0)

Then I execute it:

let results = try! db.prepare(query)

And I can then use first(where predicate: (Element) throws -> Bool) to find my target:

let target = results.first { row -> Bool in
    return row.get(ItemsTableExpressions.id) == targetID
}