null Questions
34
Solved
How do I determine if a variable is undefined or null?
My code is as follows:
var EmpName = $("div#esd-names div#name").attr('class');
if(EmpName == 'undefined'){
// DO SOMETHING
};
<...
Baneful asked 15/4, 2010 at 18:12
9
Solved
How do I check a variable if it's null or undefined and what is the difference between the null and undefined?
What is the difference between == and === (it's hard to search Google for "===" )?
Longinus asked 24/2, 2011 at 8:10
6
Solved
I ran into code similar to this today.
SELECT AuditDomain,
ObjectId,
AuditSubdomain = CONVERT(VARCHAR(50), NULL),
SubDomainObjectId = CONVERT(INT, NULL)
FROM Audit
It seems to imply that dat...
Drift asked 26/3, 2013 at 21:16
7
Solved
I quite often come across data that is structured something like this:
employees <- list(
list(id = 1,
dept = "IT",
age = 29,
sportsteam = "softball"),
list(id = 2,
dept = "IT",
age = 30...
Soapbox asked 4/4, 2014 at 18:15
16
Solved
Should you set all the objects to null (Nothing in VB.NET) once you have finished with them?
I understand that in .NET it is essential to dispose of any instances of objects that implement the ID...
Centurion asked 5/8, 2008 at 20:14
11
Solved
Theoretically I can say that
free(ptr);
free(ptr);
is a memory corruption since we are freeing the memory which has already been freed.
But what if
free(ptr);
ptr=NULL;
free(ptr);
As the...
Subtle asked 21/12, 2009 at 7:43
3
Solved
I have a dataframe with "id" column and a column which has an array of struct. The schema:
root
|-- id: string (nullable = true)
|-- desc: array (nullable = false)
| |-- element: struc...
Grille asked 7/5, 2018 at 13:17
6
Solved
When using the Java 8 Optional class, there are two ways in which a value can be wrapped in an optional.
String foobar = <value or null>;
Optional.of(foobar); // May throw NullPointerExcepti...
Squally asked 29/7, 2015 at 9:30
10
If entity.getHistory() is null following code snippet:
(getEntityManager() returns spring injected EntityManager, database field history type is: text or varchar2(2000)
Query query = getEntityMan...
Paucity asked 21/11, 2011 at 11:38
9
Solved
When using integer columns is it better to have 0 or NULL to indicate no value.
For example, if a table had a parent_id field and a particular entry had no parent, would you use 0 or NULL?
I hav...
Softfinned asked 16/2, 2011 at 11:44
2
Solved
edit: Stupid. The problem was that I got a string with value 'null'
How to compare for null in groovy correctly?
I've got the following script
println "row6: " + row[6]
if(row[6] == null) {
...
Forficate asked 19/12, 2014 at 9:37
7
Solved
I have a lot of comparisons that I need to make between a value and its previous value.
For Example: ReceivedBy and PreviousReceivedBy.
I started with:
WHERE ReceivedBy != PreviousReceivedBy
B...
Nim asked 18/6, 2018 at 20:40
9
Solved
I'm having a problem where when I try to select the rows that have a NULL for a certain column, it returns an empty set. However, when I look at the table in phpMyAdmin, it says null for most of th...
8
Solved
This code:
SELECT JSON_EXTRACT('{"hello": null}', '$.hello')
Returns null.
However, this is not the MySQL native NULL. For example, this:
SELECT COALESCE(JSON_EXTRACT('{"hello": null}', '$.hel...
7
Solved
I need to declare a type such that removes the undefined from its property types.
Suppose we have:
type Type1{
prop?: number;
}
type Type2{
prop: number | undefined;
}
type Type3{
prop: numb...
Demurral asked 29/10, 2018 at 16:34
10
6
Solved
Spark 2.4 introduced new useful Spark SQL functions involving arrays, but I was a little bit puzzled when I found out that the result of
select array_remove(array(1, 2, 3, null, 3), null) is null a...
Deluge asked 12/1, 2019 at 13:17
5
Solved
I have a simple post that works in a test app
Controller Code
public ActionResult Delete(string Id)
{
... delete record ...
}
JavaScript
function delAnnouncement(id) {
$.ajax({
type: "POST"...
Vector asked 31/7, 2014 at 3:11
6
Solved
I've recently discovered that this:
if (Foo() != null)
{ mymethod(); }
can be rewritten as:
Foo?.mymethod()
Can the following be rewritten in a similar fashion?
if (Foo == null)
{ throw new Exc...
Gehenna asked 17/2, 2016 at 23:44
6
I have a nested for ... in loop in Vue.js. What I'm trying to do is to skip elements if the value of the element is null. Here is the Vue template code:
<ul>
<li v-for="item in items...
Messina asked 24/3, 2016 at 16:48
2
Solved
I use Kotlin to Programm Android Apps. For null-pointer safety one needs to check if all references are non-null. However if only one is null then we should inform the user that something went wron...
1
My visual's x-axis is Date, aggregated by month, and the y-axis is total sales (sum of costs). For some months, I had no sales, but Quicksight ignores these and only shows me the months that do hav...
Shaky asked 8/8, 2019 at 18:27
10
Solved
I have a function which I have written which basically looks like this:
function getNextCard(searchTerms) {
// Setup Some Variables
// Do a bunch of logic to pick the next card based on termed ...
Verticillaster asked 23/6, 2016 at 0:53
5
Solved
I wish to model a value which can have two possible forms: absent, or a string.
The natural way to do this is with Maybe String, or Optional<String>, or string option, etc. However, Go does ...
Washy asked 9/6, 2015 at 12:10
3
Uncaught (in promise) TypeError: Cannot convert undefined or null to object
at Function.keys (<anonymous>)
at companion-bubble.js:1465:19726
at Generator.next (<anonymous>)
at Ln (c...
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