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问题 I am currently receiving an error when trying to execute a simple SELECT statement that references an assembly that contains the C# code for the Jaro-Winkler distance algorithm. This is my first time working with SQLCLRs. I am able to run the code successfully below without the additional OR statement Example: SELECT * FROM USERS WHERE ( DATE_OF_BIRTH IS NOT NULL AND DBO.JAROWINKLER(CONVERT(VARCHAR(6),DATE_OF_BIRTH,12),@DOB) > 0.9 ) OR ( USERID = @USERID ) However when I include the OR

问题 In R often the NULL value is used as default. Using Python and RPy2, how can one explicitly provide a NULL argument? None is not convertible ( NotImplementedError ), a string 'NULL' will just be converted to a string and result in an error during execution. Take the following example using the tsintermittent package: import numpy as np from rpy2.robjects.packages import importr from rpy2.robjects import numpy2ri numpy2ri.activate() tsintermittent = importr('tsintermittent') crost =

问题 In R often the NULL value is used as default. Using Python and RPy2, how can one explicitly provide a NULL argument? None is not convertible ( NotImplementedError ), a string 'NULL' will just be converted to a string and result in an error during execution. Take the following example using the tsintermittent package: import numpy as np from rpy2.robjects.packages import importr from rpy2.robjects import numpy2ri numpy2ri.activate() tsintermittent = importr('tsintermittent') crost =

问题 In R often the NULL value is used as default. Using Python and RPy2, how can one explicitly provide a NULL argument? None is not convertible ( NotImplementedError ), a string 'NULL' will just be converted to a string and result in an error during execution. Take the following example using the tsintermittent package: import numpy as np from rpy2.robjects.packages import importr from rpy2.robjects import numpy2ri numpy2ri.activate() tsintermittent = importr('tsintermittent') crost =

问题 This question already has answers here : F# how to return have value a tuple or null (3 answers) Closed 24 days ago . I have this type-correct C# function: static System.Tuple<int,int> f(int n) { switch (n) { case 0: return null; default: return System.Tuple.Create(n,n+1); } } I try to re-implement it in F#: let f = function | 0 -> null | n -> System.Tuple.Create(n, n+1) Type-checker disagrees, though: error FS0001: The type '('a * 'b)' does not have 'null' as a proper value. How do I re

问题 Basically the title. I see a lot of the former in the code I'm working on and I was wondering why they didn't use the latter. Are there any differences between the two? Thanks. 回答1: Straight from the documentation Unlike the Equals method and the equality operator, the ReferenceEquals method cannot be overridden. Because of this, if you want to test two object references for equality and are unsure about the implementation of the Equals method, you can call the ReferenceEquals method. However

问题 I would like to identify the number of null values in each column in all tables.I have a data base it consist of around 250 tables.Most of them are in use.The problem is almost all tables contain unwanted columns which created for some short term use.Now we want to identify columns with null values for all tables.Since the count of table is large and time is less.I would like to know an easiest way to identify null record count on each table in column wise. I tried this query which i got from

问题 I'm creating an admin with easy admin bundle, i'm really new to Symfony4. I've a button "create a category" and when i click on it, I've this error : Return value of App\Entity\Category::getCreatedAt() must implement interface DateTimeInterface, null returned Code: <?php namespace App\Entity; use DateInterval; use DateTimeZone; use Doctrine\Common\Collections\ArrayCollection; use Doctrine\Common\Collections\Collection; use DateTimeInterface; use Doctrine\ORM\Mapping as ORM; /** * @ORM\Entity

问题 I have created a custom abstract class, which in turn of course derived classes were also created. public abstract class AbstractBaseClass ... public class ChildClass1 : AbstractBaseClass ... Now, whenever I declare for example AbstractBaseClass baseClass = null , and wherever null checks follow after this initialization, it always fails. if (baseClass == null) { // this block is never reached - condition always evaluates to false // let's say AbstractBaseClass baseClass = null is at line 10

问题 This question already has answers here : Java null check why use == instead of .equals() (16 answers) Closed 7 years ago . What's the best way to check for not null values in java. String query ="abcd"; query != null vs !query.equals(null). which is better?why? 回答1: 1st one is better (and the only option ), because 2nd one will throw NPE , when your value is actually null . As simple as that. Try this out: String str = null; str.equals(null); // will throw `NPE`. So basically, the test which