W3Schools
w3schools.com βΊ sql βΊ sql_null_values.asp
SQL NULL Values - IS NULL and IS NOT NULL
SQL Examples SQL Editor SQL Quiz SQL Exercises SQL Server SQL Syllabus SQL Study Plan SQL Bootcamp SQL Certificate SQL Training ... A field with a NULL value is a field with no value.
special marker and keyword in SQL indicating that something has no value
Factsheet
Null (SQL)
Notation Ο
Null (SQL)
Notation Ο
Wikipedia
en.wikipedia.org βΊ wiki βΊ Null_(SQL)
Null (SQL) - Wikipedia
1 week ago - NULL is a special marker used to indicate that a data value does not exist in the database. Introduced by the creator of the relational database model, E. F. Codd, SQL null serves to fulfill the requirement that all true relational database management systems (RDBMS) support a representation ...
Videos
01:03:16
How to handle NULL in SQL - YouTube
08:29
SQL to find NULL in any column - YouTube
12:19
Learn about NULL values in SQL - learn SQL pt 8 - YouTube
04:46
Understanding NULL Values in SQL | What NULL Means and How to Use ...
11:40
How To Handle NULL Values In MS SQL Server? - YouTube
11:18
Working with SQL NULL values | Null Handling Functions - YouTube
Microsoft Learn
learn.microsoft.com βΊ en-us βΊ sql βΊ t-sql βΊ language-elements βΊ null-and-unknown-transact-sql
NULL and UNKNOWN (Transact-SQL) - SQL Server | Microsoft Learn
Applies to: SQL Server Azure SQL ... Warehouse in Microsoft Fabric SQL database in Microsoft Fabric Β· NULL indicates that the value is unknown....
Top answer 1 of 16
234
Think of the null as "unknown" in that case (or "does not exist"). In either of those cases, you can't say that they are equal, because you don't know the value of either of them. So, null=null evaluates to not true (false or null, depending on your system), because you don't know the values to say that they ARE equal. This behavior is defined in the ANSI SQL-92 standard.
EDIT: This depends on your ansi_nulls setting. if you have ANSI_NULLS off, this WILL evaluate to true. Run the following code for an example...
set ansi_nulls off
if null = null
print 'true'
else
print 'false'
set ansi_nulls ON
if null = null
print 'true'
else
print 'false'
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156
How old is Frank? I don't know (null).
How old is Shirley? I don't know (null).
Are Frank and Shirley the same age?
Correct answer should be "I don't know" (null), not "no", as Frank and Shirley might be the same age, we simply don't know.
W3Schools
w3schools.com βΊ sql βΊ sql_isnull.asp
SQL IFNULL(), ISNULL(), COALESCE(), and NVL() Functions
SQL Examples SQL Editor SQL Quiz SQL Exercises SQL Server SQL Syllabus SQL Study Plan SQL Bootcamp SQL Certificate SQL Training ... Suppose that the "UnitsOnOrder" column is optional, and may contain NULL values.
W3Schools
w3schools.com βΊ mysql βΊ mysql_null_values.asp
MySQL NULL Values - IS NULL and IS NOT NULL
The IS NULL operator is used to test for empty values (NULL values). The following SQL lists all customers with a NULL value in the "Address" field:
Tutorialspoint
tutorialspoint.com βΊ sql βΊ sql-null-values.htm
SQL - NULL Values
SQL uses the term NULL to represent a non-existent data value in the database. These values are not the same as an empty string or a zero. They don't hold any space in the database and are used to signify the absence of a value or the unknown value in a data field.
SQL Shack
sqlshack.com βΊ working-with-sql-null-values
Working with SQL NULL values
May 19, 2021 - If we widen this theoretical explanation, the NULL value points to an unknown value but this unknown value does not equivalent to a zero value or a field that contains spaces. Due to this structure of the NULL values, it is not possible to use traditional comparison (=, <, > and <>) operators in the queries. As a matter of fact, in the SQL Standards using the WHERE clause as the below will lead to return empty result sets.
Baeldung
baeldung.com βΊ home βΊ sql queries βΊ find null or empty values in sql
Find Null or Empty Values in SQL Baeldung on SQL
August 20, 2025 - NULL values in SQL represent missing or unknown data in a database column. This can occur for two reasons: the data does not exist, or it exists but is currently unknown. In contrast, an empty value, such as an empty string, is a specific value ...
Modern SQL
modern-sql.com βΊ concept βΊ null
Modern SQL: NULL β purpose, comparisons, NULL in expressions, mapping to/from NULL
SQLβs NULL indicates absent data. NULL propagates through expressions and needs distinct comparison operators.
DbSchema
dbschema.com βΊ blog βΊ tutorials βΊ sql-null-values
SQL NULL Values Explained with Examples
In this article, we will discuss ... and FAQs related to this topic. In SQL, NULL is a special marker used to indicate that a data value does not exist in the database....
SQLBolt
sqlbolt.com βΊ lesson βΊ select_queries_with_nulls
SQLBolt - Learn SQL - SQL Lesson 8: A short note on NULLs
Select query with constraints on NULL values SELECT column, another_column, β¦ FROM mytable WHERE column IS/IS NOT NULL AND/OR another_condition AND/OR β¦; This exercise will be a sort of review of the last few lessons. We're using the same Employees and Buildings table from the last lesson, but we've hired a few more people, who haven't yet been assigned a building. Sorry but the SQLBolt exercises require a more recent browser to run.
DataLemur
datalemur.com βΊ sql-tutorial βΊ sql-null
Handling NULL Values | DataLemur
In SQL, indicates the absence of a value. Unlike an empty string or zero, doesn't represent a specific value, but rather, a missing or unknown piece of information. Here's an overview of what you'll learn in this tutorial: ... Handling NULL ...
Reddit
reddit.com βΊ r/learnsql βΊ what is a null in sql? is it the same as a empty cell?
r/learnSQL on Reddit: What is a null in sql? is it the same as a empty cell?
October 5, 2022 -
Lets say i have a Excel sheet , col : name and ID . some rows cells in "name" are empty in datasheet.
now sql pulls this data, will the empty cells be filled with a null value by default?
or is null a unique type of character that is only used to overwrite existing values , so when system reads it it thinks its empty?
Top answer 1 of 5
12
NULL, in simplest terms, is the absence of data. Not to be confused with '', an empty string. If you are familiar with other languages, you could think of it as similar to undefined, in that the column has a type defined, but the specific cell has no data, and is more of a place holder for future data. When filtering for NULL, you will need to do things like table.col is null or table.col is not null In your Excel example, it depends on how you import the data, and what the definition of the target table is. The target table may have rules built into it to default the data for certain columns, or reject NULL values from other columns. You could have Null, an empty string, zero, weird dates.. etc.
2 of 5
3
NULL Is not equal to empty cell. Empty cells can sometimes contain space in the cell and you'll not be able to filter these out with NULL For Empty cells you could use LEN() in Excel.
W3Schools
w3schools.com βΊ sql βΊ sql_ref_is_null.asp
SQL IS NULL
SQL Examples SQL Editor SQL Quiz SQL Exercises SQL Server SQL Syllabus SQL Study Plan SQL Bootcamp SQL Certificate SQL Training ... The IS NULL command is used to test for empty values (NULL values).
ThoughtSpot
thoughtspot.com βΊ sql-tutorial βΊ sql-is-null
SQL IS NULL | Basic SQL | ThoughtSpot
3 weeks ago - This SQL tutorial covers how to work with null values by using SQL's IS NULL operator to select rows where a column contains no data.
GeeksforGeeks
geeksforgeeks.org βΊ sql βΊ sql-select-null
SQL - SELECT NULL - GeeksforGeeks
July 23, 2025 - In SQL, the term NULL represents a missing or undefined value in a table. A NULL value is different from a zero or an empty string; it signifies that no data exists for that field.
Reddit
reddit.com βΊ r/sql βΊ need some knowledge on null and not null
r/SQL on Reddit: Need some knowledge on NULL and NOT NULL
December 22, 2021 -
Where and why exactly a null is used?
What is exactly null and not null? To my understanding Not null we use when its mandatory to insert some value in that field, also when we give check constraint so by default the column will be not null right?
By adding new column through alter method default values are null, so how would I be able to insert values in it and is it right to give not null constraint to that new column while adding through alter method, basically when null and when not null to be used?...
god this is so confusing please help me, ik im asking alot but im really confused
Top answer 1 of 5
8
a null is used for multiple purposes -- for example, not known, not applicable, etc. theoreticians take great joy in debating which uses are valid, and whether they can be substituted by some non-null placeholder suffice to say, a null is used when you don't know what value should go there if you don't want that situation to arise, just make the column NOT NULL and you'll never be able to not insert an actual value
2 of 5
3
Thoughts in this can vary but I'll give my input. NULL should be used where it is known that there can definitely be no value. If a person's record has an optional telephone number when signing up to a website, and they do not complete a number upon their submission, then a NULL is a valid value. However, if we are utilising something like "effective from" and "effective to" of a row of data, then effective to should never be NULL, we always determine that a row is either currently effective, or is historic and superceded. As a result, the "active" row should not hold a NULL in effective to, even though it is not known. It should be a future, default date, and the column should be set with a NOT NULL constraint.
GeeksforGeeks
geeksforgeeks.org βΊ sql βΊ sql-null-values
NULL values in SQL - GeeksforGeeks
July 23, 2025 - In SQL, some records in a table may not have values for every field, and such fields are termed as NULL values. These occur when data is unavailable during entry or when the attribute does not apply to a specific record.
Scaler
scaler.com βΊ topics βΊ sql βΊ null-value-in-sql
NULL Value in SQL - Scaler Topics
April 20, 2022 - NULL value in SQL signifies that the column's corresponding value is either undefined or unknown.