How to use NULL or empty string in SQL

Question

I would like to know how to use NULL and an empty string at the same time in a WHERE clause in SQL Server. I need to find records that have either null values o

Answer 1

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

Answer 2

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)),'')<>''

Answer 3

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.

Answer 4

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

Answer 5

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'

Answer 6

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,'') = '';