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 or an empty string  Thanks

User · Answer

You can simply do this   SELECT   FROM   yourTable WHERE  yourColumn IS NULL OR yourColumn

User · Answer

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       lt  gt

User · Answer

SELECT   FROM   TableName WHERE  columnNAme IS NULL OR         LTRIM RTRIM columnName

User · Answer

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

User · Answer

--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

User · Answer

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

User · Answer

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

User · Answer

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

User · Answer

select     isnull column     column     from Table   Where column

User · Answer

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

User · Answer

This is ugly MSSQL   CASE WHEN LTRIM RTRIM ISNULL  Address1          lt  gt     THEN  Address2  ELSE    END

User · Answer

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  gt    DT START   --FILTER  -- MORE FILTER  SELECT   FROM DBO AGENDA WHERE        ISNULL   DT START           AND DT START IS NOT NULL   OR   DT START  gt    DT START        AND   DT END  lt  GETDATE

User · Answer

SELECT   FROM   Table WHERE  column like    or column IS NULL OR LEN column    0

User · Answer

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

User · Answer

Select   From Table Where  col is null or col         Or  Select   From Table Where IsNull col

User · Answer

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  lt  gt     0 1    1   SELECT   FROM  T WHERE NULLIF SomeCol     IS NULL   SELECT   FROM  T WHERE ISNULL SomeCol

[sql] How to use NULL or empty string in SQL

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