Convert SQL Statement to Predicate or NSExpression

Question

I am facing a problem with converting below SQL to NSExpression

SELECT id,trait1,trait2,trait3,sum(trait1+trait2+trait3) as total FROM `bookings` GROUP BY id order by total desc

Below is my code in this code I am only able to add the two key values not three key values.

func aggregateProductsInContext(context:NSManagedObjectContext) {

    var expressionDescriptions = [AnyObject]()
    expressionDescriptions.append("name")

    let expressionDescription = NSExpressionDescription()
    expressionDescription.name = "Sold"

    let exp1 = NSExpression(forKeyPath: "trait1")
    let exp3 = NSExpression(forKeyPath: "trait2")
    let exp3 = NSExpression(forKeyPath: "trait3")

    let stas = NSExpression(forFunction:"add:to:", arguments:[exp1,exp3])

    expressionDescription.expression = stas
    expressionDescription.expressionResultType = .Integer64AttributeType
    expressionDescriptions.append(expressionDescription)
    let request = NSFetchRequest(entityName: "booking")
    request.propertiesToGroupBy = ["name"]
    request.resultType = .DictionaryResultType
    request.sortDescriptors = [NSSortDescriptor(key: "name", ascending: true)]
    request.propertiesToFetch = expressionDescriptions



    var results:[[String:AnyObject]]?

    do {
        results = try context.executeFetchRequest(request) as? [[String:AnyObject]]
    } catch _ {
        results = nil
    }



print(results)

}

Please find the attached images of actual table values and resulted values for reference.

Thanks!

My Solution:

I am able to solve my problem by doing this

let ec = NSExpression(forFunction:"add:to:", arguments:[exp1,exp2])
let ec1 = NSExpression(forFunction:"add:to:", arguments:[ec,exp3])
let ec2 = NSExpression(forFunction:"add:to:", arguments:[ec1,exp4])
let ec3 = NSExpression(forFunction:"add:to:", arguments:[ec2,exp5])

If there is any other way to achieve this, please let me know

Thanks!

see this solution http://stackoverflow.com/a/22398620/2031707 — Punita, Sep 21 '16 at 14:01
Have you considered using the `sum:` function with `NSExpression`? — Tom Harrington, Sep 21 '16 at 17:13
@Punita I don't want to do the Sum of all values of a column. I want to sum the multiple column values of one row — Karamjeet Singh, Sep 22 '16 at 03:17

score 0 · Answer 1 · answered Sep 22 '16 at 04:54

Here is the solution which I had implemented and it's work fine.

let ec = NSExpression(forFunction:"add:to:", arguments:[exp1,exp2])
let ec1 = NSExpression(forFunction:"add:to:", arguments:[ec,exp3])
let ec2 = NSExpression(forFunction:"add:to:", arguments:[ec1,exp4])
let ec3 = NSExpression(forFunction:"add:to:", arguments:[ec2,exp5])

But I am sure there must be some other good way to do that. If any one have any other solution. please let me know.

Thanks!

Convert SQL Statement to Predicate or NSExpression

1 Answers1