special marker and keyword in SQL indicating that something has no value
Factsheet
Null (SQL)
Notation ω
Null (SQL)
Notation ω
Wikipedia
en.wikipedia.org › wiki › Null_(SQL)
Null (SQL) - Wikipedia
5 days ago - In an Oracle RDBMS, for example, ... Since Null is not a member of any data domain, it is not considered a "value", but rather a marker (or placeholder) indicating the undefined value....
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
Oracle
docs.oracle.com › en › database › other-databases › timesten › 22.1 › sql-reference › null-values.html
Null Values
July 25, 2025 - The value NULL indicates the absence of a value. It is a placeholder for a value that is missing. Use a NULL when the actual value is not known or when a value would not be meaningful. Do not use NULL to represent a numeric value of zero, because they are not equivalent.
Null in SQL ,what does it store
Null is a state, not a value. It doesn’t store nothing, it is not nothing, it is not equal to itself. It indicates that we do not know, or cannot know, or perhaps that nothing can be known. Null isn’t not, but isn’t not not, nor is it. tl;dr - “there is no value recorded” More on reddit.com
59
34
June 24, 2025[Oracle SQL] How can I return a specific row if no rows are retrieved in my query?
Sounds to me like you want to return a default value. My SQL is rusty but I think you need a conditional statement or 3 with the EXISTS() function. Of course the real question is, why are you doing this in SQL and not whatever language you are programming the rest of your app in. More on reddit.com
20
7
January 14, 2019[ORACLE] Selecting a null value to an integer variable but an "if (A = null) then..." statement wont run
To be clear 'A' is a variable defined as an integer . Another sql statement selects an auto key value(produced by a sequence command) and the goals is to run the SQL anytime the return is a null value on the auto key value. The SQL statement creates a record on a particular table with certain values pulled from various tables, all related to each other through various auto key (sequence) values.
More on reddit.com 10
1
April 24, 2014Oracle SQL Developer - Need null value if record doesn't exist
Why dont you just put the SSN numbers into a new table and than join it to the data table you are using. You can then outer join it and get all the results plus the problem with 1000 records in the IN clause will disapear.
More on reddit.com 4
2
February 8, 2019Oracle
docs.oracle.com › en › database › oracle › oracle-database › 19 › sqlrf › Nulls.html
SQL Language Reference
November 12, 2025 - If a column in a row has no value, then the column is said to be null, or to contain null. Nulls can appear in columns of any data type that are not restricted by NOT NULL or PRIMARY KEY integrity constraints. Use a null when the actual value is not known or when a value would not be meaningful.
GeeksforGeeks
geeksforgeeks.org › sql › sql-null-values
NULL values in SQL - GeeksforGeeks
January 5, 2026 - Since it is often not possible to determine which interpretation applies, SQL treats all NULL values as distinct and does not distinguish between them. Typically, it can have one of three interpretations: Value Unknown: The value exists but is not known. Value Not Available: The value exists but is intentionally withheld. Attribute Not Applicable: The value is undefined for a specific record. Setting a NULL value is appropriate when the actual value is unknown, or when a value is not meaningful.
Oracle
docs.oracle.com › database › 121 › SQLRF › sql_elements005.htm
Nulls
If you use any other condition with nulls and the result depends on the value of the null, then the result is UNKNOWN. Because null represents a lack of data, a null cannot be equal or unequal to any value or to another null. However, Oracle considers two nulls to be equal when evaluating a DECODE function. Refer to DECODE for syntax and additional information.
Modern SQL
modern-sql.com › concept › null
Modern SQL: NULL — purpose, comparisons, NULL in expressions, mapping to/from NULL
Expressions and functions that process a null value generally return the null value.4 Noteworthy exceptions are aggregate functions and—due to the three-valued logic of SQL—two logical operations.5 · The result of the following expressions is therefore null: ... The Oracle database treats an empty string as null and vice versa: on the one hand, '' IS NULL is true, on the other hand is null treated as an empty string in string concatenations (||).
Tutorials
onlinetutorialhub.com › home › oracle sql › how to handle null in oracle sql? & what is null handling?
How to Handle NULL in Oracle SQL? & What is NULL Handling?
September 8, 2025 - No matter what kind of data it contains, a column is deemed NULL if it contains no values. Remembering that a NULL is not the same as zero or a blank space is crucial. An unknown age for a person in an age-tracking table, for instance, is NULL rather than zero since zero would suggest a known ...
IONOS UK
ionos.co.uk › digital guide › server › configuration › sql nvl
How to use SQL NVL - IONOS UK
February 26, 2025 - The function checks the records ... information you’ve indicated. NULL values usually represent a lack of data in a row or column. They are not the same as the numerical value ‘0’ or spaces.
W3Schools
w3schools.com › sql › sql_null_values.asp
SQL 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:
DB Vis
dbvis.com › thetable › dealing-with-null-in-sql-complete-guide
Dealing With NULL in SQL: Complete Guide
April 9, 2025 - In SQL, NULL represents missing or unknown values in a database table. Unlike zero or an empty string, NULL signifies the absence of a value–not zero, not an empty string, but a true unknown or undefined value.
Oracle
docs.oracle.com › en › database › other-databases › nosql-database › 20.3 › sqlreferencefornosql › is-null-and-is-not-null-operators.html
IS NULL and IS NOT NULL Operators
The IS NULL operator tests whether the result of its input expression is NULL. If the input expression returns more than one item, an error is raised. If the result of the input expression is empty, IS NULL returns false. Otherwise, IS NULL returns true if and only if the single item computed ...
Oracle-Base
oracle-base.com › articles › misc › null-related-functions
NULL-Related Functions - ORACLE-BASE
Instead they must use the IS NULL or IS NOT NULL operators. SQL> SELECT * FROM null_test_tab WHERE col1 IS NULL ORDER BY id; ID COL1 COL2 COL3 COL4 ---------- ---------- ---------- ---------- ---------- 2 TWO THREE FOUR 3 THREE FOUR 4 THREE THREE 3 rows selected. SQL> The NVL function allows you to replace null values with a default value.
TechOnTheNet
techonthenet.com › oracle › isnull.php
Oracle / PLSQL: IS NULL Condition
If expression is not a NULL value, the condition evaluates to FALSE. Here is an example of how to use the Oracle IS NULL condition in a SELECT statement: SELECT * FROM suppliers WHERE supplier_name IS NULL; This Oracle IS NULL example will return all records from the suppliers table where the supplier_name contains a null value.
Medium
medium.com › @DigitalFootprints › how-to-handle-null-values-in-oracle-database-a4110bf8243a
How to handle NULL values in Oracle database | by BK | Medium
September 20, 2023 - When the expression is equal to the value, it would return the value. If no match is found, then it returns default. If there is no default argument, then it returns NULL.
Reddit
reddit.com › r/sql › null in sql ,what does it store
r/SQL on Reddit: Null in SQL ,what does it store
June 24, 2025 -
What do null in sql store
Top answer 1 of 19
262
Null is a state, not a value. It doesn’t store nothing, it is not nothing, it is not equal to itself. It indicates that we do not know, or cannot know, or perhaps that nothing can be known. Null isn’t not, but isn’t not not, nor is it. tl;dr - “there is no value recorded”
2 of 19
25
Null is the lack of information or the none existence of it. Let's say for example you made a shopping list and as you went round the shop you were writing the price down. Let's say dragon fruit is on your list and the shop doesn't sell it then it would have a price of "null". It doesn't mean dragon fruit has a price of "nothing" it means we don't have information or it doesn't exist.
Tutorialspoint
tutorialspoint.com › sql › 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
DZone
dzone.com › data engineering › databases › null in oracle
NULL in Oracle
August 17, 2023 - Due to the peculiarities of the three-valued logic, NOT IN is not friendly with NULLs at all: as soon as NULL gets into the selection conditions, do not wait for the data. Here Oracle deviates from the ANSI SQL standard and declares the equivalence of NULL and the empty string.
Hightouch
hightouch.com › sql-dictionary › sql-is-null
SQL IS NULL - Syntax, Use Cases, and Examples | Hightouch
December 29, 2023 - A NULL value in a database represents the absence of data, and the IS NULL operator is used to identify and select rows that contain NULL values in a particular column. You would use the SQL IS NULL operator when you need to filter data from ...
LearnSQL.com
learnsql.com › blog › what-is-null-in-sql
What Is a NULL in SQL? | LearnSQL.com
March 17, 2021 - Simply put, an SQL NULL means that we don’t have a value for that particular field.
MariaDB
mariadb.com › docs › server › reference › data-types › null-values
NULL Values | Server | MariaDB Documentation
UNIQUE indexes can contain multiple NULL values. Primary keys are never nullable. ... In Oracle mode, CONCAT and the Logical OR operator || ignore null. When setting sql_mode=EMPTY_STRING_IS_NULL, empty strings and NULL values are the same thing.