Is there any difference between a NULL and a Blank field in MS SQL

• shameersinbox

  SSC-Addicted

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  October 14, 2008 at 4:20 am

  #194447

  My question is, is there any difference between a NULL and a Blank

  field in MS SQL or are they the same?

  I have faced some problems while retrieving the records from the database.How to overcome......

  Any one help

  Thanks

  Shameer

• Chandra Sekhara Vyas Dhara

  SSChampion

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  October 14, 2008 at 4:36 am

  #884512

  Both are different.Null is value which is unknown.

  If you want to extract the null values use is null

  If you want to extract blank values use = ' '

• rajasekhar.bollareddy

  SSC Enthusiast

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  February 25, 2011 at 3:30 am

  #1291433

  insert into employee(emp_no,emp_fname,emp_lname,dept_no) values(29346,null,'james','d2')

  10102annjonesd3

  18316johnbarrimored1

  25348matthewsmithd3

  29346jamesjamesd2

  29347NULLjamesd2

  insert into employee(emp_no,emp_lname,dept_no) values(29346,'james','d2')

  10102annjonesd3

  18316johnbarrimored1

  25348matthewsmithd3

  29346jamesjamesd2

  29347NULLjamesd2

  so no difference both are same

• Carlton Leach

  SSCarpal Tunnel

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  February 25, 2011 at 4:43 am

  #1291453

  rajasekhar.bollareddy (2/25/2011)

  ---

  so no difference both are same

  An empty string an NULL are the same? Nope.

  As stated NULL is an unknown value not an empty string (we know it's a string, we know it's empty).

  If your having trouble retrieving things from a column that could be either use ISNULL (look in books online). Use with caution as this can be a performance nightmare.

  Carlton.

• Johan Bijnens

  SSC Guru

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  February 25, 2011 at 5:24 am

  #1291463

  If to you NULL = '' then declare you column NOT NULL !! (maybe even add "with default '' )

  there are some nice article regarding NULL and its impact for mistakes .... to happen ....

  -http://www.sqlservercentral.com/articles/Advanced+Querying/2829/

  - http://www.sqlservercentral.com/articles/T-SQL/understandingthedifferencebetweenisnull/871/

  - http://www.sqlservercentral.com/articles/ANSI_NULLs/69234/

  - http://www.sqlservercentral.com/articles/Advanced+Querying/gotchasqlaggregatefunctionsandnull/1947/

  - http://www.sqlservercentral.com/articles/Advanced/2921/

  Johan
  
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