It is fine to have null values in data sets. If something can be NULL you are saying, it’s okay to not have it. You just need to make sure that when operating on something that could be null you are checking before operating on it. If(possiblyNullValue) {console.log(“it’s not null”)} Answer from JbREACT on reddit.com
Khoury College of Computer Sciences
khoury.northeastern.edu › home › kenb › MeaningOfNull.html
The Meaning of Null in Databases and Programming Languages
That certainly is true in this case, so there is a good argument for using the default value. The field has a value but it is not within the domain. For example, a form requesting an ethnic group does not include the one to which a person most closely identifies. The NULL in this case represents ...
Navicat
navicat.com › en › company › aboutus › blog › 1312-the-null-value-and-its-purpose-in-relational-database-systems
The NULL Value and its Purpose in Relational Database Systems
March 3, 2020 - Here's an example that excludes films from the Sakila database that contain a NULL original_language_id: Likewise, you can find out which rows contain a NULL value by dropping the NOT from the NOT NULL clause. Now, only those rows with a NULL original_language_id are returned: In today's blog, we explored what the NULL value means and how to work with this special value in relational databases.
Where do NULL values come from in datasets and how to handle them?
It is fine to have null values in data sets. If something can be NULL you are saying, it’s okay to not have it. You just need to make sure that when operating on something that could be null you are checking before operating on it. If(possiblyNullValue) {console.log(“it’s not null”)} More on reddit.com
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June 8, 2024What is Null?
This was intended as a meme but is actually a good representation of what "Null" is. In C#, when you declare string s = "My shit"; it means that "s" is a reference to a memory location that holds the data "My shit". string s = null; means that the reference "s" exists but it's not pointing to any object, as in it holds nothing. More on reddit.com
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July 5, 2024What is NULL in SQL? - Stack Overflow
In simple worlds you can say that Null is not a data value, but a marker for an unknown value. So any mathematical operations performed on NULL will result in NULL. For example, ... So you can say that Null means either "not applicable" or "don't know": it is not the same as zero (0) or any ... More on stackoverflow.com
[Q] What does a P value of above 0.05 mean?
I guess I don’t interpret “not significantly different” as meaning that they are trying to claim that “we proved that they are the same”. Saying that they didn’t find a significant difference, to me, is simply saying that they failed to reject the null. More on reddit.com
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July 15, 2023Videos
02:48
Database Systems - NULL Values - YouTube
01:00
What are NULL values? - YouTube
03:28
Definition: What is a Null Value? - YouTube
04:46
Understanding NULL Values in SQL | What NULL Means and How to Use ...
01:03:16
How to handle NULL in SQL - YouTube
03:19
Null Values - YouTube
Biztory
biztory.com › home › blog › 7 things you should know about null values
7 Things to know about NULL values - Biztory | Biztory
October 25, 2025 - Some people have a nasty tendency to impute the mean or an arbitrary value (e.g. 99, 100, 0, -1) directly into the database. If a value appears suspiciously often or seems impossible; it might be an attempt to input NULL values. ... Just to name a couple of examples: I once saw a database where all of the customers who made a purchase before 2005 had an age of 27.
W3Schools
w3schools.com › sql › sql_null_values.asp
SQL NULL Values - IS NULL and IS NOT NULL
It is not possible to test for NULL values with comparison operators, such as =, <, or <>. We will have to use the IS NULL and IS NOT NULL operators instead. SELECT column_names FROM table_name WHERE column_name IS NULL; SELECT column_names FROM table_name WHERE column_name IS NOT NULL; Below is a selection from the Customers table used in the examples:
Reddit
reddit.com › r/learnprogramming › where do null values come from in datasets and how to handle them?
r/learnprogramming on Reddit: Where do NULL values come from in datasets and how to handle them?
June 8, 2024 -
My understanding is that NULL represents true absence of value or a total unknown value. This is not the same as empty which is a known value, or a string of zero length. I've worked with banking data and often see lots of NULL values in various fields but if NULL represents UNKNOWN does that mean something simply went wrong/error in the system or is it a legitimate value? Because otherwise I'd think putting empty there makes more sense.
Not really sure how to treat NULL values in these datasets, should I simply ignore them? What if I'm trying to transform the data (or preform joins) on these rows wouldn't NULL values throw all the calculations off?
How should I think about and handle NULL values as they come into my codebase?
Thanks
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It is fine to have null values in data sets. If something can be NULL you are saying, it’s okay to not have it. You just need to make sure that when operating on something that could be null you are checking before operating on it. If(possiblyNullValue) {console.log(“it’s not null”)}
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NULL values can mean whatever you want them to mean, and different people have different opinions on how they should be used. Generally, the only way they will enter your database is because you insert them -- either explicitly by using NULL as a value in an INSERT statement, or implicitly, by not specifying a value for a column whose default is NULL. Probably the most common reason to use NULL is to represent an "optional" value. For instance, maybe in a banking application, you have a user table with a "social security number" field. Some of your users might be US residents who have an SSN, and others might be foreigners who don't. This could be considered a "true absence of value" because it's not the case that the person has an SSN which is "empty", they simply don't have one. It doesn't necessarily make sense to allow a "missing" or NULL value for every field, which is why databases allow you to easily declare which fields are nullable or non-nullable in your schema. Can you explain why you think using NULL would "throw all the calculations off"? It's true that NULL has different behavior than an empty string, but that might be exactly what you want. For instance, if you perform a join on the SSN field, you probably wouldn't want every possible pair of users with a missing SSN to be joined with each other. Two empty strings are considered "equal", but two NULL values are not.
IBM
ibm.com › docs › en › rbd › 9.6.0
Null values and the nullable type - IBM Documentation
February 10, 2022 - Reference variables (variables that contain an address for data rather than the data itself) are always nullable, which means they are automatically capable of having a null value. What makes the idea complex is that you can make value variables nullable as well. The main advantage you get from making a variable nullable is the ability to test it to see if it has a useful value, as in the following example:
Wikipedia
en.wikipedia.org › wiki › Null_(SQL)
Null (SQL) - Wikipedia
1 day ago - Computer science professor Ron van der Meyden summarized the various issues as: "The inconsistencies in the SQL standard mean that it is not possible to ascribe any intuitive logical semantics to the treatment of nulls in SQL." Although various proposals have been made for resolving these issues, the complexity of the alternatives has prevented their widespread adoption. Because Null is not a data value, but a marker for an absent value, using mathematical operators on Null gives an unknown result, which is represented by Null. In the following example, multiplying 10 by Null results in Null:
HistoryNull propagationComparisons with NULL and the three-valued logic (3VL)Analysis of SQL Null missing-value semanticsCheck constraints and foreign keysOuter joinsAggregate functionsWhen two nulls are equal: grouping, sorting, and some set operationsEffect on index operationNull-handling functionsData typing of Null and UnknownBOOLEAN data typeControversyFurther reading
Broadcom
ftpdocs.broadcom.com › cadocs › 0 › CA IDMS 18 5 User Bookshelf-ENU › Bookshelf_Files › HTML › IDMS_SQL_Ref_ENU › 976467.html
Null Values
You use the keyword NULL to indicate a null value. For example, the following INSERT statement inserts a new row into the DEPARTMENT table. The department number and name and the division code are known, but the department head has not been appointed yet.
MDN Web Docs
developer.mozilla.org › en-US › docs › Web › JavaScript › Reference › Operators › null
null - JavaScript - MDN Web Docs
Semantically, their difference is very minor: undefined represents the absence of a value, while null represents the absence of an object. For example, the end of the prototype chain is null because the prototype chain is composed of objects; document.querySelector() returns null if it doesn't ...
MSSQLTips
mssqltips.com › home › sql null meaning and how to handle null values
SQL NULL Meaning and How to Handle NULL Values
June 20, 2024 - It seemed best to introduce it at the top. It accepts two parameters: a value and a replacement. The function attempts to return the first value, but if that value is NULL, then the second parameter, the replacement, is returned instead. In this example, the variable is never set and remains NULL.
Essential SQL
essentialsql.com › home › what is a database null value?
What is a Database NULL Value? - Essential SQL
March 4, 2023 - In SQL, this is solved with null. It is used to signify missing or unknown values. The keyword NULL is used to indicate these values. NULL really isn’t a specific value as much as it is an indicator.
GeeksforGeeks
geeksforgeeks.org › sql › sql-null-values
NULL values in SQL - GeeksforGeeks
January 5, 2026 - Some records in an SQL table may not have values for every field, and such fields are termed NULL values. These occur when data is unavailable during entry or when an attribute does not apply to a specific record.
DB Vis
dbvis.com › thetable › the-definitive-guide-to-the-null-sql-server-value
The Definitive Guide to the NULL SQL Server Value
September 12, 2024 - Read this article to ensure that your knowledge of NULL values is not null! In SQL Server, NULL indicates data that is unknown, not applicable, or yet to be provided. For example, assume a column for a middle name is nullable.
Reddit
reddit.com › r/learnprogramming › what is null?
r/learnprogramming on Reddit: What is Null?
July 5, 2024 -
So I use C# and I often see many devs use null.
What and which kind of situation do you use this variable?
I am reading c# guide on programming book and I am on Clearing memory now and I haven't encountered null yet. Should I be worried?
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This was intended as a meme but is actually a good representation of what "Null" is. In C#, when you declare string s = "My shit"; it means that "s" is a reference to a memory location that holds the data "My shit". string s = null; means that the reference "s" exists but it's not pointing to any object, as in it holds nothing.
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NULL is nothing. It means theres nothing there. Often its just a place holder before something is there. Say u have a bunch of variables of animals. U might set them to NULL before u know what they are. Then u might check if they are NULL before u add an animal to them. Things are initialized as NULL.
4JS
4js.com › online_documentation › fjs-fgl-manual-html › fgl-topics › c_fgl_sql_programming_nulls.html
Genero Business Development Language - The NULL value
Several considerations need to be taken regarding SQL columns allowing NULL values. The SQL concept of NULL means "no value" or "undefined value".
freeCodeCamp
freecodecamp.org › news › a-quick-and-thorough-guide-to-null-what-it-is-and-how-you-should-use-it-d170cea62840
A quick and thorough guide to ‘null’: what it is, and how you should use it
June 12, 2018 - It means that there is no value associated with name. You can also think of it as the absence of data or simply no data. Note: The actual memory value used to denote null is implementation-specific.
DbSchema
dbschema.com › blog › tutorials › sql null values – is null, coalesce, nullif, and common pitfalls | dbschema
SQL NULL Values – IS NULL, COALESCE, NULLIF, and Common Pitfalls | DbSchema
August 22, 2023 - NULL is a special marker that means "no value exists here." Understanding NULL is essential because it affects filtering, aggregation, joins, comparisons, and even subqueries in ways that surprise many developers.
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In simple worlds you can say that Null is not a data value, but a marker for an unknown value.
So any mathematical operations performed on NULL will result in NULL. For example,
10 + NULL = NULL
Similarly if you do string concatenation with string you get:-
'String ' || NULL || 'Concatenation' -- Result is NULL
So you can say that Null means either "not applicable" or "don't know": it is not the same as zero (0) or any other default value, but more importantly, null is treated quite differently from other values in SQL, because it literally has no value.
An example to explain what it means when we say that NULL means UNKNOWN VALUE:
StudentName TestResult
X 78
A 89
B 67
C NULL
So you can see that the student C got NULL marks in the test. So what does that mean?
Now one can say that the student does not sit in the test or it may be that the student's data is not avaialable. But it definitely does not mean that the student got 0(as if you assign 0 to the student then it would mean that the student appeared in the test and got zero) marks in the test. All we can say that the data for the student is
UNKNOWN or NULL
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A field with a NULL value is a field with no value. It is very important to understand that a NULL value is different than a zero value or a field that contains spaces.
If a column in a table is optional, we can insert a new record or update an existing record without adding a value to this column. This means that the field will be saved with a NULL value.
NULL values are treated differently from other values.
NULL is used as a placeholder for unknown or inapplicable values. Read more about this here.
Microsoft Learn
learn.microsoft.com › en-us › dotnet › framework › data › adonet › sql › handling-null-values
Handling Null Values - ADO.NET | Microsoft Learn
September 15, 2021 - Use the IS NULL or IS NOT NULL predicate to test for a null value. This can add complexity to the WHERE clause. For example, the TerritoryID column in the AdventureWorks Customer table allows null values.