How to use NULL or empty string in SQL

Select *
From Table
Where (col is null or col = '')

Or

Select *
From Table
Where IsNull(col, '') = ''

If you need it in SELECT section can use like this.

SELECT ct.ID, 
 ISNULL(NULLIF(ct.LaunchDate, ''), null) [LaunchDate]
FROM [dbo].[CustomerTable] ct

You can replace the null with your substitution value.

You can simply do this:

SELECT *
FROM yourTable
WHERE yourColumn IS NULL OR yourColumn = ''

SELECT *
FROM TableName
WHERE columnNAme IS NULL OR 
 LTRIM(RTRIM(columnName)) = ''

To find rows where col is NULL, empty string or whitespace (spaces, tabs):

SELECT *
FROM table
WHERE ISNULL(LTRIM(RTRIM(col)),'')=''

To find rows where col is NOT NULL, empty string or whitespace (spaces, tabs):

SELECT *
FROM table
WHERE ISNULL(LTRIM(RTRIM(col)),'')<>''

Some sargable methods...

SELECT *
FROM #T
WHERE SomeCol = '' OR SomeCol IS NULL;
SELECT *
FROM #T
WHERE SomeCol = '' 
UNION ALL
SELECT *
FROM #T
WHERE SomeCol IS NULL;
SELECT *
FROM #T
WHERE EXISTS ((SELECT NULL UNION SELECT '') INTERSECT SELECT SomeCol);

And some non-sargable ones...

SELECT *
FROM #T
WHERE IIF(SomeCol <> '',0,1) = 1;
SELECT *
FROM #T
WHERE NULLIF(SomeCol,'') IS NULL;
SELECT *
FROM #T
WHERE ISNULL(SomeCol,'') = '';

my best solution :

 WHERE 
 COALESCE(char_length(fieldValue), 0) = 0

COALESCE returns the first non-null expr in the expression list().

if the fieldValue is null or empty string then: we will return the second element then 0.

so 0 is equal to 0 then this fieldValue is a null or empty string.

in python for exemple:

def coalesce(fieldValue):
 if fieldValue in (null,''):
 return 0

good luck

SELECT *
FROM Table
WHERE column like '' or column IS NULL OR LEN(column) = 0

You could use isnull function to get both null and empty values of a text field:

SELECT * FROM myTable
WHERE isnull(my_nullable_text_field,'') = ''

This is ugly MSSQL:

CASE WHEN LTRIM(RTRIM(ISNULL([Address1], ''))) <> '' THEN [Address2] ELSE '' END

select 
 isnull(column,'') column, * 
from Table 
Where column = ''

You can use in as another method

Select *
From Table
Where column in(null, '')

--setup
IF OBJECT_ID('tempdb..#T') IS NOT NULL DROP TABLE #T;
CREATE TABLE #T(ID INT NOT NULL IDENTITY(1,1) PRIMARY KEY, NAME VARCHAR(10))
INSERT INTO #T (Name) VALUES('JOHN'),(''),(NULL);
SELECT * FROM #T
 1 JOHN
 2 -- is empty string
 3 NULL

You can examine '' as NULL by converting it to NULL using NULLIF

--here you set '' to null
UPDATE #T SET NAME = NULLIF(NAME,'')
SELECT * FROM #T 
 1 JOHN
 2 NULL
 3 NULL

or you can examine NULL as '' using SELECT ISNULL(NULL,'')

-- here you set NULL to ''
UPDATE #T SET NAME = ISNULL(NULL,'') WHERE NAME IS NULL
SELECT * FROM #T
1 JOHN
2 -- is empty string
3 -- is empty string
--clean up
DROP TABLE #T

In sproc, you can use the following condition:

DECLARE @USER_ID VARCAHR(15)=NULL --THIS VALUE IS NULL OR EMPTY DON'T MATTER
IF(COALESCE(@USER_ID,'')='')
PRINT 'HUSSAM'

by this function:

ALTER FUNCTION [dbo].[isnull](@input nvarchar(50),@ret int = 0)
RETURNS int
AS
BEGIN
 return (case when @input='' then @ret when @input is null then @ret else @input end)
END

and use this:

dbo.isnull(value,0)

SELECT * FROM DBO.AGENDA
WHERE 
 --IF @DT_START IS NULL OR EMPTY
 ( ISNULL( @DT_START,'' ) = '' AND DT_START IS NOT NULL ) -- GET ALL DATE
 OR --ELSE
 ( DT_START >= @DT_START ) --FILTER
-- MORE FILTER
SELECT * FROM DBO.AGENDA
WHERE 
 ( ( ISNULL( @DT_START,'' ) = '' AND DT_START IS NOT NULL ) OR ( DT_START >= @DT_START ) ) 
 AND
 DT_END < GETDATE()

youe check null With IS NULL and string Empty With LEN(RTRIM(LTRIM(Column))) = 0 in

SELECT *
FROM AppInfra.Person
WHERE LEN(RTRIM(LTRIM(NationalCode))) = 0 OR NationalCode IS NULL

If you need it in SELECT section can use like this.

SELECT COALESCE(column1, column2) AS columnName
FROM tabel;

if column1 is null column2 will be return

if you want to fetch empty and null values from one column then this code apply

select columnname2 from tablename
where columnname2 is null or columnname2 = '';

select columnlist from table you want to fetch then where in which column you want to fetch values of null then write columnname is null and also you want to find empty values then write perticular column name then = '' this will show that empty values from perticular column

• sql
• sql-server
• null
• where-clause