constraints

问题 It is possible to create constraint in Neo4J database for attribute to be not null? Something like: CREATE CONSTRAINT ON (p:Person) ASSERT p.name IS NOT NULL 回答1: It's planned and been already implemented for Neo4j 2.3, should be available with 2.3.RC1 来源： https://stackoverflow.com/questions/31439614/not-null-attribute-in-neo4j-constraint

问题 I believe using autoresizing for orientational changes would be good while managing the UI with Autolayout. So many programmers are recommending against both at the same time,But As far as I understand it should be fine. Because Autoresizingmask is easy to play with. I think autoresizing mask itself turns into constraints actually I believe translatesAutoresizingMaskIntoConstraints Correct me If I am wrong If its okay or not okay can some explain in depth why ? 回答1: As far as I am aware it is

问题 I believe using autoresizing for orientational changes would be good while managing the UI with Autolayout. So many programmers are recommending against both at the same time,But As far as I understand it should be fine. Because Autoresizingmask is easy to play with. I think autoresizing mask itself turns into constraints actually I believe translatesAutoresizingMaskIntoConstraints Correct me If I am wrong If its okay or not okay can some explain in depth why ? 回答1: As far as I am aware it is

问题 I have a class that has a Generic type "G" In my class model i have public class DetailElement : ElementDefinition Let's say i have a method like this public void DoSomething<G>(G generic) where G : ElementDefinition { if (generic is DetailElement) { ((DetailElement)generic).DescEN = "Hello people"; //line 1 ////// ElementDefinition element = generic; ((DetailElement)element).DescEN = "Hello again"; //line 3 ////// (generic as DetailElement).DescEN = "Howdy"; //line 5 } else { //do other

问题 I am trying to create a table where the values in one column can't be greater than the next column over. For example, I am creating the following table. CREATE TABLE Price ( PriceID INT PRIMARY KEY IDENTITY (1,1), OriginalPrice FLOAT NOT NULL, CurrentPrice FLOAT NOT NULL, Discount FLOAT, ShippingCost FLOAT NOT NULL, Tax FLOAT NOT NULL); And Current Price cannot be greater than OriginalPrice. So what I tried doing was CurrentPrice FLOAT CHECK (CurrentPrice <= OriginalPrice) NOT NULL, But this

问题 I'm trying to create some tables and setup the foreign keys but I keep encountering problems with the foreign keys. Earlier on I created the below table and it works fine CREATE TABLE inpatient (PatientNo varchar(6) NOT NULL, WardNo number(2), BedNo number(3) NOT NULL, OnWaitingList date, WardRequired varchar(25), ExpectStayInDays number(4), DatePlaced date, DateLeave date, ActualLeave date, constraint PatientFK foreign key (PatientNo) references Patient (patientNo), constraint bedFK foreign

问题 Question 1 - Basic LUBConstraints My first try playing around with existing LUBConstraints fails for missing evidence (see code block below). Any hint why? Isn't an empty list a valid list of longs? no element violates the constraint. import shapeless.ops.coproduct import shapeless.{::, :+:, Coproduct, HNil, HList} object testLUBConstraints { import shapeless.LUBConstraint._ // !!! see comment on question - this satisfies the implicit below!!! // implicit val hnilLUBForLong = new

问题 I am using the following formula: =MIN(IF(A1:A5>B1,A1:A5)) use Ctrl-Shift-Enter My value for B1 is 10 and my array is {1,5,4,2,7} so in this case no value is greater than 10. The problem is that excel returns 0 as the result of the empty set which is a problem as 0 is not greater than 10. In this case, I can test if the result 0 is greater than 10 and see that the result is invalid, however, if B1 is -10 for an array of {-15,-24,-11,-37-60} than the 0 seems like a valid value when no correct

问题 Can someone provide a simple example of channelling constraints? Channelling constraints are used to combine viewpoints of a constraint problem. Handbook of Constraint Programming gives a good explanation of how it works and why it can be useful: The search variables can be the variables of one of the viewpoints, say X1 (this is discussed further below). As search proceeds, propagating the constraints C1 removes values from the domains of the variables in X1. The channelling constraints may

问题 I'm creating an SQL table that needs the fields from=date and to=date but I'd like to make a constraint so that to cannot be before from . My program will check for it but I'd like to learn how to enforce it with SQL. I've written SQL before but never really used constraints and don't know how they work. So the question is: Using standard SQL, how do I make sure that From is before To ? 回答1: create table foo ( from_date date, to_date date, constraint check_dates check (from_date < to_date) );