CopySelect *
From Table
Where (col is null or col = '')
Or
CopySelect *
From Table
Where IsNull(col, '') = ''
Answer from codingbadger on Stack Overflow Top answer 1 of 16
378
CopySelect *
From Table
Where (col is null or col = '')
Or
CopySelect *
From Table
Where IsNull(col, '') = ''
2 of 16
72
If you need it in SELECT section can use like this.
CopySELECT ct.ID,
ISNULL(NULLIF(ct.LaunchDate, ''), null) [LaunchDate]
FROM [dbo].[CustomerTable] ct
You can replace the null with your substitution value.
W3Schools
w3schools.com › sql › sql_null_values.asp
SQL NULL Values - IS NULL and IS NOT NULL
SELECT column_names FROM table_name ... a selection from the Customers table used in the examples: The IS NULL operator is used to test for empty values (NULL values)....
How to replace NULL with Empty String in SQL Server? ISNULL() vs COALESCE() Examples
Remember, COALESCE() is a standard function and whenever you can use COALESCE() you should be using it. The reason for using ISNULL() instead of COALESCE() lies in the differences between the two that were not addressed in this blog post. ISNULL() returns the same datatype as the single input expression, whereas COALESCE() has to determine the return type based on the types from all of the expressions. Also, I reject the idea that in every database engine you should only use the "standard" functions. Nobody is going to run the same SQL I write for SQL Server on another database engine without a lot of rewriting, so why throw away the power of using platform specific functions? You'd be hog tied trying to do anything with string or date manipulation if you lived by those rules. More on reddit.com
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October 4, 2024What is a null in sql? is it the same as a empty cell?
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. More on reddit.com
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October 5, 2022difference between ISNULL and IF <thing> IS NULL?
ISNULL is more readable and more concise, and imo should be preferred to the 'IF' syntax. IF IS NULL only has the advantage of being portable when using different RDBMs (ISNULL is specific to SQL Server - it'll be NVL in Oracle for example) More on reddit.com
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November 8, 2013design - SQL: empty string vs NULL value - Software Engineering Stack Exchange
I know this subject is a bit controversial and there are a lot of various articles/opinions floating around the internet. Unfortunatelly, most of them assume the person doesn't know what the differ... More on softwareengineering.stackexchange.com
Videos
01:47
SQL short ISNULL. What is ISNULL and how does it work. - YouTube
16:14
NULL vs BLANK vs EMPTY in SQL: Understand the Differences & How ...
17:05
SQL NULL vs Empty String vs Blank Space (Visually Explained) | ...
09:52
Practice Activity: Replacing NULL and blank values in Microsoft ...
05:17
SQL SERVER||ISNULL() Vs IS NULL - YouTube
SQLServerCentral
sqlservercentral.com › home › topics › check the variable is empty or null
Check the Variable is Empty or Null – SQLServerCentral Forums
September 9, 2014 - Edit: sql code tag messed up my "greater than" symbol. You may do it... sometimes... But it is NOT right. Try this: ... If you want to make sure that your varchar value contains some thingelse than NULL and empty string use simple "NOT EQUAL" eg:
GeeksforGeeks
geeksforgeeks.org › sql server › how-to-check-a-column-is-empty-or-null-in-sql-server
How to Check a Column is Empty or Null in SQL Server - GeeksforGeeks
January 31, 2024 - If we check the below query you ... Remarks IS NOT NULL ... The function ISNULL() returns all records with 'NULL' values and records having Empty value ('') or Spaces (' ') in the specified column....
Devart
devart.com › home › how to › how to handle null or empty values in sql server
How to Handle Null or Empty Values in SQL Server
December 19, 2024 - ISNULL(…, ‘Not provided’) replaces any NULL values (whether originally NULL or transformed to NULL by NULLIF) with the string Not provided. ... In SQL Server, you can use conditional expressions, such as CASE, along with functions like ...
Microsoft Learn
learn.microsoft.com › en-us › sql › t-sql › functions › isnull-transact-sql
ISNULL (Transact-SQL) - SQL Server | Microsoft Learn
ISNULL replaces NULL with the specified replacement value.
Reddit
reddit.com › r/sqlserver › how to replace null with empty string in sql server? isnull() vs coalesce() examples
r/SQLServer on Reddit: How to replace NULL with Empty String in SQL Server? ISNULL() vs COALESCE() Examples
October 4, 2024 - If you are just wanting a blank string instead of a null then use isnull(FieldName,’’). Or you came just default to column to a blank string. What is the use case of coalesce (not what it does)? ... Making varchar default to empty string vs.
W3Schools
w3schools.com › Sql › sql_isnull.asp
W3Schools.com
The COALESCE() function works in MySQL, SQL Server, and Oracle (not in MS Access). ... The MySQL IFNULL() function replaces NULL with a specified value. ... The SQL Server ISNULL() function replaces NULL with a specified value.
Medium
medium.com › @esegui › isnull-in-sql-server-and-other-null-functions-72ada1a98e56
ISNULL in SQL Server (and other NULL functions) | by Emmanuel Segui | Medium
April 22, 2024 - SELECT * FROM Employees WHERE ISNULL(FirstName, '') = '' In this example, the WHERE clause checks for records where the FirstName column is NULL or empty.
Baeldung
baeldung.com › home › sql queries › find null or empty values in sql
Find Null or Empty Values in SQL Baeldung on SQL
August 20, 2025 - The ISNULL function in MS SQL takes ... value if the first argument is null. This query retrieves rows where the code column is either null, an empty string, or contains only spaces....
Quora
quora.com › What-is-the-standard-SQL-query-for-checking-null-or-empty-strings
What is the standard SQL query for checking null or empty strings? - Quora
To check for empty strings, you can use the IS NULL predicate along with the LENGTH function (or its equivalent for your database system) to check if the length of the string is zero.
Reddit
reddit.com › r/learnsql › 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.
Microsoft Learn
learn.microsoft.com › en-us › sql › mdx › working-with-empty-values
Working with Empty Values - SQL Server | Microsoft Learn
January 27, 2025 - If empty values are stored in your underlying fact table data, by default they will be converted to zeroes when the cube is processed. You can use the Null Processing option on a measure to control whether null facts are converted into 0, converted ...
SQLNetHub
sqlnethub.com › home › blog › handling null and empty values in sql server
Handling NULL and Empty Values in SQL Server - SQLNetHub
December 12, 2024 - Unfortunately there is not a “magic” formula for that. The only suggestion is not to use empty strings but use NULL values instead which can be handled by the ISNULL, NULLIF and COALESCE functions.
IONOS
ionos.com › digital guide › server › configuration › sql isnull
How to check and replace NULL values with SQL ISNULL() - IONOS
January 21, 2025 - If you do not assign a value to a field within the table, this field remains empty and is assigned the value NULL, indicating no actual value. Suppose you want to ensure that a substitute value is used instead of NULL.
Microsoft Learn
learn.microsoft.com › en-us › sql › t-sql › language-elements › null-and-unknown-transact-sql
NULL and UNKNOWN (Transact-SQL) - SQL Server | Microsoft Learn
... Applies to: SQL Server Azure ... Fabric Warehouse in Microsoft Fabric SQL database in Microsoft Fabric · NULL indicates that the value is unknown....
Reddit
reddit.com › r/sql › difference between isnull and if is null?
r/SQL on Reddit: difference between ISNULL and IF <thing> IS NULL?
November 8, 2013 -
Whenever I need a different value if a column is null, I use the isnull function because, well, that's why it's there, right?
A friend of mine, however, swears by the 'if <column> is null, ..' syntax. As far as I can tell, this is the same thing, it's just a different syntax.
However, different syntax can mean that other things are happening under water, so I became curious as to what the difference was, but was unable to find it on google :/
Top answer 1 of 5
4
ISNULL is more readable and more concise, and imo should be preferred to the 'IF' syntax. IF IS NULL only has the advantage of being portable when using different RDBMs (ISNULL is specific to SQL Server - it'll be NVL in Oracle for example)
2 of 5
4
According to idera's SQL doctor, isnull in a where clause can cause index suppression, and thus table scans, since it's a function. Is not null should allow full use of indexes. As has been said, isnull() is best in your select, since you can effectively replace nulls there.
Scaler
scaler.com › home › topics › sql server isnull() function
What is SQL Server ISNULL() Function? - Scaler Topics
March 8, 2024 - ISNULL(@value, 5) checks if @value is NULL. Since it is, it returns 5. ... This feature is especially useful when displaying data to end users or performing calculations when NULL values could disrupt the desired results.
W3Schools
w3schools.com › sql › sql_ref_is_null.asp
SQL IS NULL
Environ IsDate IsNull IsNumeric SQL Quick Ref · SQL Examples SQL Editor SQL Quiz SQL Exercises SQL Server SQL Syllabus SQL Study Plan SQL Bootcamp SQL Training ... The IS NULL command is used to test for empty values (NULL ...
Top answer 1 of 12
89
I would say that NULL is the correct choice for "no email address". There are many "invalid" email addresses, and "" (empty string) is just one. For example "foo" is not a valid email address, "a@b@c" is not valid and so on. So just because "" is not a valid email address is no reason to use it as the "no email address" value.
I think you're right in saying that "" is not the correct way to say "I don't have a value for this column". "" is a value.
An example of where "" might be a valid value, separate to NULL could be a person's middle name. Not every one has a middle name, so you need to differentiate between "no middle name" ("" - empty string) and "I don't know if this person has a middle name or not" (NULL). There's probably many other examples where an empty string is still a valid value for a column.
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While agreeing with the above comments, I would add this argument as a primary motivation:
- It is obvious to any programmer looking at a database that a field marked NULL is an Optional field. (i.e. the record doesn't require data for that column)
- If you mark a field NOT NULL, any programmer should intuitively assume that it is a Required field.
- In a field that allows nulls, programmers should expect to see nulls rather than empty strings.
For the sake of Self-Documenting Intuitive Coding, use NULL instead of empty strings.