I use this all the time. Especially when Im summing data from a join, I need to make any null fields a 0 so it will sum correctly. There are other non numeric uses too, like “grab this field from this table but if it’s empty, then grab this field from that table”. You don’t always want to show null. Answer from MyLastGamble on reddit.com
Microsoft Learn
learn.microsoft.com › en-us › sql › t-sql › language-elements › coalesce-transact-sql
COALESCE (Transact-SQL) - SQL Server | Microsoft Learn
Applies to: SQL Server Azure SQL ... in Microsoft Fabric · Evaluates the arguments in order and returns the current value of the first expression that initially doesn't evaluate to NULL....
Reddit
reddit.com › r/sql › what is the use case of coalesce (not what it does)?
r/SQL on Reddit: What is the use case of coalesce (not what it does)?
June 17, 2022 -
I know exactly what coalesce does and I have used it once. Literally, once. It can be used to replace a null value with some other value like zero. But as someone who is new to working with data, what I don't understand is why I would want to do that. Why do I want to replace a null value with zero instead of just letting it be null in the data?
Top answer 1 of 13
40
I use this all the time. Especially when Im summing data from a join, I need to make any null fields a 0 so it will sum correctly. There are other non numeric uses too, like “grab this field from this table but if it’s empty, then grab this field from that table”. You don’t always want to show null.
2 of 13
24
LEFT JOIN. Main data is in table A, but complementary data might be on B or C. So SELECT A.name , COALESCE(B.department, C.department) as Department FROM A LEFT JOIN B ON A.id= B.id LEFT JOIN C ON A.id = C.id Also adding two numbers as someone else said. 5+NULL = NULL, but I often want it to be 5.
Videos
02:57
How to Use the COALESCE Function in SQL - YouTube
Coalesce Function in SQL Server: An Intermediate Tutorial - YouTube
14:10
COALESCE function in SQL | SQL for Data Professionals |Topic #22 ...
09:43
A Difference Between ISNULL And COALESCE You Might Care About In ...
09:28
SQL Server Coalesce Function | Billy Thomas | ALLJOY Data - YouTube
05:33
COALESCE Function in SQL - YouTube
What does the COALESCE function do in SQL?
The COALESCE function returns the first non-NULL value from a list of expressions, making it useful for handling missing or incomplete data.
red-gate.com
red-gate.com › home › why coalesce might be the most useful sql function you’re not using right
Why COALESCE might be the most useful SQL function you’re not ...
When should you NOT use the SQL COALESCE function?
Avoid using the SQL COALESCE function when replacing NULL(s) – it could change the meaning of your data, especially in analytics or reporting where NULL represents unknown values.
red-gate.com
red-gate.com › home › why coalesce might be the most useful sql function you’re not using right
Why COALESCE might be the most useful SQL function you’re not ...
What is the syntax of COALESCE?
The basic syntax is:
COALESCE(value1, value2, ..., valueN)
It evaluates each value in order and returns the first one that is not NULL.
red-gate.com
red-gate.com › home › why coalesce might be the most useful sql function you’re not using right
Why COALESCE might be the most useful SQL function you’re not ...
W3Schools
w3schools.com › sql › func_sqlserver_coalesce.asp
SQL Server COALESCE() Function
SQL Examples SQL Editor SQL Quiz SQL Exercises SQL Server SQL Syllabus SQL Study Plan SQL Bootcamp SQL Training ... The COALESCE() function returns the first non-null value in a list.
Hightouch
hightouch.com › sql-dictionary › sql-coalesce
SQL COALESCE - Syntax, Use Cases, and Examples | Hightouch
December 29, 2023 - The SQL COALESCE function is used to handle NULL values in a database query by returning the first non-NULL value from a list of expressions or column values. It allows you to provide a default or fallback value when NULL values are encountered ...
Oracle
docs.oracle.com › en › database › oracle › oracle-database › 26 › sqlrf › COALESCE.html
SQL Language Reference
May 11, 2026 - COALESCE returns the first non-null expr in the expression list. You must specify at least two expressions.
DataCamp
datacamp.com › tutorial › coalesce-sql-function
How to Use the COALESCE() Function in SQL (With Examples) | DataCamp
March 27, 2025 - Learn how to use the SQL COALESCE() function to handle null values, combine columns, and clean up your data with real-world examples and tips.
Medium
stevesohcot.medium.com › i-found-a-use-for-the-sql-coalesce-function-e9a133c2d03f
I found a use for the SQL COALESCE() Function | by Steve Sohcot | Medium
February 21, 2023 - The COALESCE() function returns the first non-null value in a list.
IBM
ibm.com › docs › en › db2-for-zos › 12.0.0
COALESCE scalar function - Db2 SQL
The COALESCE function returns the value of the first nonnull expression.
Red Gate Software
red-gate.com › home › why coalesce might be the most useful sql function you’re not using right
Why COALESCE might be the most useful SQL function you’re not using right
May 7, 2026 - The SQL COALESCE function provides a simple, standard way to return the first available (non-NULL) value from a list -making it a go-to tool for cleaning data, setting defaults, and building resilient queries across modern databases.
InterSystems
docs.intersystems.com › irisforhealthlatest › csp › docbook › DocBook.UI.Page.cls
COALESCE (SQL) | InterSystems SQL Reference | InterSystems IRIS for Health 2026.1
COALESCE - A function that returns the value of the first expression that is not NULL.
Databricks
docs.databricks.com › sql language reference › functions › built-in functions › alphabetical list of built-in functions › coalesce function
coalesce function | Databricks on AWS
> SELECT coalesce(2, 5 / 0); 2 > SELECT coalesce(NULL, 'hello'); hello
Databricks Documentation
docs.databricks.com › sql language reference › functions › built-in functions › alphabetical list of built-in functions › coalesce function
coalesce function | Databricks on Google Cloud
July 26, 2024 - > SELECT coalesce(2, 5 / 0); 2 > SELECT coalesce(NULL, 'hello'); hello
W3Schools
w3schools.com › Sql › sql_isnull.asp
W3Schools.com
SQL has some built-in functions to handle NULL values, and the most common functions are: COALESCE() - The preferred standard.
Top answer 1 of 3
2
You must have a typo, or some other simple reason.
It is very easy to verify, just return both a.id and COALESCE(a.id, a.id) in the same query together. Make sure to use aliases, so that you know that you are looking at a.id and not id from some other table.
SELECT
a.id AS a_id,
COALESCE(a.id, a.id) AS filled_id,
a.name, a.website, a.lat, a.long, a.primary_poc, a.sales_rep_id, o.*
FROM accounts a
LEFT JOIN orders o
ON a.id = o.account_id
WHERE o.total IS NULL;
2 of 3
0
For this example you've provided, if a.id is null of course the second a.id will be null.
COALESCE is helpful with left joins for e.g
select coalesce(DE.user_id, KBU.user_id, OUD.user_id) as User_ID
LEFT JOIN dm.EDW.DIM_Employee DE
ON de.user_id = RIGHT(SubQuery.[UserID], LEN(SubQuery.[UserID]) - 5)
AND de.dss_current_flag = 'Y'
AND de.Dss_Deleted_Flag = 'N'
-- Some of the users are missing from our Dim Table so need to use other sources
LEFT JOIN tts..load_KBNetwork_Users KBU
ON KBU.UID = RIGHT(SubQuery.[UserID], LEN(SubQuery.[UserID]) - 5)
LEFT JOIN dm.dbo.organisationunitdimension OUD
ON oud.OrgUnitLevel5SourceId = RIGHT(SubQuery.[UserID], LEN(SubQuery.[UserID]) - 5)
AND oud.dss_current_flag = 'Y'
if DE is null then I can get the first null value from the next two (if possible)
Runsql
runsql.com › blog › posts › 2025-02-28-sql-coalesce-guide
COALESCE in SQL – The Ultimate Guide to Handling NULLs and Fallback Values | dbdiagram Blog
February 28, 2025 - COALESCE is a powerful SQL function for handling NULL values by returning the first non-null value in a list. This guide explores its syntax, use cases, database-specific implementations, performance considerations, and best practices.
AWS
docs.aws.amazon.com › aws kinesis data analytics › sql reference › functions › null functions › coalesce
COALESCE - Amazon Kinesis Data Analytics SQL Reference
The COALESCE function takes a list of expressions (all of which must be of the same type) and returns the first non-null argument from the list. If all of the expressions are null, COALESCE returns null.
Snowflake Documentation
docs.snowflake.com › en › sql-reference › functions › coalesce
COALESCE | Snowflake Documentation
Snowflake performs implicit conversion of arguments to make them compatible. For example, if one of the input expressions is a numeric type, the return type is also a numeric type. That is, SELECT COALESCE('17', 1); first converts the VARCHAR value '17' to the NUMBER value 17, and then returns ...
Medium
medium.com › @deepa.account › understanding-coalesce-function-in-sql-and-spark-f9bf31100503
Understanding Coalesce function in SQL and Spark | by Deepa Vasanthkumar | Medium
August 26, 2024 - The COALESCE function is a powerful and commonly used feature in both SQL and Apache Spark. It is instrumental in handling NULL values and optimizing resource usage, which are crucial in data engineering and processing.
SQL Academy
sql-academy.org › articles & tutorials › sql coalesce: what it is and how it works — examples | sql academy
SQL COALESCE: What It Is and How It Works — Examples | SQL Academy
1 week ago - COALESCE is a function that takes a list of arguments and returns the first one that is not NULL. Its most common use is substituting a default value for NULL in query results. ... It works identically in every popular DBMS: MySQL, PostgreSQL, ...