W3Schools
w3schools.com › sql › 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 ... If a field in a table is optional, it is possible to insert or update a record without adding any value to this field...
Mimo
mimo.org › glossary › sql › is-not-null
SQL IS NOT NULL Condition: Syntax, Usage, and Examples
# SQL IS NOT NULL: Syntax, Usage, and Examples The `SQL IS NOT NULL` condition checks whether a column contains a value rather than being empty. In SQL, a `NULL` represents missing or undefined data—not the number zero, an empty string, or false. Use `IS NOT NULL` to return rows where values ...
Need some knowledge on NULL and NOT NULL
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 More on reddit.com
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December 22, 2021sql - NULL vs NOT NULL - Stack Overflow
In sql database column, empty fields will be set to NULL unless we specify it using NOT NULL. What are the advantages of using one instead of the other? Thanks! More on stackoverflow.com
"NOT NULL" property in SQL Server Express 2019
Good evening everyone, I have been exploring this new tool (for myself) and ran into an issue that I cannot explain. I have been using SQL 2008 and never had that problem. The case is that within SQL 2019 I set the "Not null" property in… More on learn.microsoft.com
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May 8, 2021What are pros and cons of using NULLS vs NOTNULLs in database?
Pros of using NULL: When your column can be NULL, NULL is a perfect fit. Pros of using NOTNULL: When your column cannot be NULL, NOTNULL is a perfect fit. Cons of using NULL: When your column cannot be NULL, NOTNULL would be a better fit. Cons of using NOTNULL: When your column can be NULL, NULL would be a better fit. More on reddit.com
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March 15, 2022Videos
W3Schools
w3schools.com › sql › sql_notnull.asp
SQL NOT NULL Constraint
This enforces a field to always contain a value, which means that you cannot insert a new record, or update a record without adding a value to this field. By default, a column can hold NULL values.
Reddit
reddit.com › r/sql › need some knowledge on null and not null
r/SQL on Reddit: Need some knowledge on NULL and NOT NULL
December 22, 2021 -
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Where and why exactly a null is used?
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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?
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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
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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
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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.
DB Vis
dbvis.com › thetable › sql-is-not-null-condition-definitive-guide
SQL IS NOT NULL Condition: Definitive Guide
August 13, 2025 - Let’s dive in! IS NOT NULL is an SQL condition used to check whether a value, expression, or column does not contain a NULL value.
Microsoft Learn
learn.microsoft.com › en-us › sql › t-sql › functions › isnull-transact-sql
ISNULL (Transact-SQL) - SQL Server | Microsoft Learn
The value of check_expression is returned if it's not NULL. Otherwise, replacement_value is returned after it's implicitly converted to the type of check_expression, if the types are different. replacement_value can be truncated if replacement_value ...
TechOnTheNet
techonthenet.com › sql_server › is_not_null.php
SQL Server: IS NOT NULL Condition
This SQL Server tutorial explains how to use the IS NOT NULL condition in SQL Server (Transact-SQL) with syntax and examples. The SQL Server (Transact-SQL) IS NOT NULL condition is used to test for a NOT NULL value.
Hightouch
hightouch.com › sql-dictionary › sql-is-not-null
SQL IS NOT NULL - Syntax, Use Cases, and Examples | Hightouch
December 29, 2023 - You would use the SQL IS NOT NULL operator when you need to filter data from a table based on whether a column's value is not NULL. This is useful when you want to retrieve records with data present in a specific column or attribute, ensuring ...
Hightouch
hightouch.com › sql-dictionary › sql-not-null
SQL NOT NULL - Syntax, Use Cases, and Examples | Hightouch
December 29, 2023 - A NOT NULL constraint in SQL is a database constraint that ensures a column must always contain a value. It prohibits the insertion of NULL values, making it mandatory for every row to have a non-null value in the specified column.
GeeksforGeeks
geeksforgeeks.org › sql › sql-not-null-constraint
SQL NOT NULL Constraint - GeeksforGeeks
February 10, 2026 - In SQL, NOT NULL constraint in SQL ensures a column must always contain a value and cannot be left empty.
TechOnTheNet
techonthenet.com › sql › is_not_null.php
SQL: IS NOT NULL Condition
This SQL tutorial explains how to use the SQL IS NOT NULL condition with syntax and examples. The IS NOT NULL condition is used in SQL to test for a non-NULL value. It returns TRUE if a non-NULL value is found, otherwise it returns FALSE.
Atlassian
atlassian.com › data › databases › how-to-alter-a-column-from-null-to-not-null-in-sql-server
How to alter a column from NULL to NOT NULL in SQL server
Changing the data structure of a column in SQL Server from NULL to NOT NULL, thereby disallowing non-null values in that column, is generally performed using the relatively simple ALTER TABLE syntax to appropriately change the column in question.
Programiz
programiz.com › sql › is-null-not-null
SQL IS NULL and IS NOT NULL (With Examples)
Here, the above SQL query retrieves all the rows from the Employee table where the value of the email column is NULL. ... Note: Empty values are considered NULL. However, space and 0 are not considered NULL. In SQL, the IS NOT NULL condition is used to select rows if the specified field is NOT NULL.
W3Schools
w3schools.com › sql › sql_ref_not_null.asp
SQL NOT NULL
String Functions: Asc Chr Concat ... SQL Bootcamp SQL Certificate SQL Training ... The NOT NULL constraint enforces a column to not accept NULL values, which means that you cannot insert or update a record without adding a value ...
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 - This sample query retrieves all employees who do not have a middle name. IS NOT NULL in SQL Server is the opposite of the IS NULL operator. That means it is used to check whether an expression does not evaluate to NULL.
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If you need to represent unknown data in a column, you make it nullable. If you will always have data in the column, it's better to make it not nullable, as
- Dealing with nulls can be annoying and counterintuitive
- It saves a bit of space
- On some database systems, null values are not indexed.
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When a field is set to NOT NULL, it cannot be empty. Which means you have to specify a value for that field when inserting a record.
Microsoft Learn
learn.microsoft.com › en-us › answers › questions › 387709 › not-null-property-in-sql-server-express-2019
"NOT NULL" property in SQL Server Express 2019 - Microsoft Q&A
May 8, 2021 - You can type the SQL expressions for the check constraint in Expression field. For example: This will apply to the fields that have the "not null" set. You also can right-click in the upper half of the screen-> select Generate Change Script to see the script about add Constraints. ... If the answer is helpful, please click "Accept Answer" and upvote it. Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.
Microsoft Learn
learn.microsoft.com › en-us › sql › t-sql › queries › is-null-transact-sql
IS NULL (Transact-SQL) - SQL Server | Microsoft Learn
... If the value of expression is NULL, IS NULL returns TRUE; otherwise, it returns FALSE. If the value of expression is NULL, IS NOT NULL returns FALSE; otherwise, it returns TRUE.
Reddit
reddit.com › r/sql › what are pros and cons of using nulls vs notnulls in database?
r/SQL on Reddit: What are pros and cons of using NULLS vs NOTNULLs in database?
March 15, 2022 -
This is specifically for data warehouse in SQL server , 3NF design. Most use cases would be writing queries to retrieve data and Tableau accessing warehouse database for reporting.
There are 2 schools of thought on Nulls vs Not nulls
What is your recommendation?
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Pros of using NULL: When your column can be NULL, NULL is a perfect fit. Pros of using NOTNULL: When your column cannot be NULL, NOTNULL is a perfect fit. Cons of using NULL: When your column cannot be NULL, NOTNULL would be a better fit. Cons of using NOTNULL: When your column can be NULL, NULL would be a better fit.
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I think your answer really depends on this: when a row gets inserted into the db, will you have all the info necessary to guarantee a given column will always be not null? If yes, feel free to use not null, if no, then you must use null. But the pros and cons are all subjective to where you want to do the work.
MSSQLTips
mssqltips.com › home › sql where is not null examples
SQL WHERE IS NOT NULL Examples
March 13, 2023 - In this article, we discussed how to use the SQL IS NOT NULL statement to select, update, insert, and delete rows and tuples based on a tuple NOT having a NULL value. ... Aubrey Love is a self-taught DBA with more than six years of experience ...