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Empy String vs. Null

Discussion in 'Information Technology' started by Paul Hammond, Nov 15, 2005.

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  1. Paul Hammond

    Paul Hammond
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    Guest

    I should know and understand this, but I don't. Could somebody please
    review the difference between these to values?

    I have a column that either contains a code or it does not, but I have to
    test for both null and "". I just can't understand the difference.

    Please 'splain it to me.

    TIA

    Paul Hammond
    --
     
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  3. Ofer

    Ofer
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    Guest

    When I filter the data, I keep in mind few things

    In a Number and date field, I check for Null
    In a Text field I check for Null and Empty

    the text field before any value been enterd into will return a Null, but if
    a value was entered into a text field, and then been deleted by the user in
    the form, will return empty.

    If I'm wrong by that I'll be happy if somebody will correct me.
    --
    I hope that helped
    Good Luck


    "Paul Hammond" wrote:

    > I should know and understand this, but I don't. Could somebody please
    > review the difference between these to values?
    >
    > I have a column that either contains a code or it does not, but I have to
    > test for both null and "". I just can't understand the difference.
    >
    > Please 'splain it to me.
    >
    > TIA
    >
    > Paul Hammond
    > --
     
  4. Douglas J Steele

    Douglas J Steele
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    Guest

    Think of Null as meaning "Unknown"

    Take a look at the Employee table in the Northwind database that came with
    Access. There are fields for information about the employee, including who
    they report to. If you were to add an employee to the table, and you didn't
    know to whom they reported, you'd leave the ReportsTo field as Null, because
    it's unknown (at least to you). Once you found out, you'd fill the field in.
    If, however, a particular person didn't report to anyone, you'd put blank
    in, because now you know to whom they report, and it's no one. (I know, not
    the greatest example, but it was the easiest to think of in terms of
    databases to which you should have access!)

    --
    Doug Steele, Microsoft Access MVP
    http://I.Am/DougSteele
    (no e-mails, please!)


    "Paul Hammond" <phammond@mediaREMOVEgeneral.com> wrote in message
    news:E4DD129E-736D-4BDE-B1D2-BD415210335A@microsoft.com...
    > I should know and understand this, but I don't. Could somebody please
    > review the difference between these to values?
    >
    > I have a column that either contains a code or it does not, but I have to
    > test for both null and "". I just can't understand the difference.
    >
    > Please 'splain it to me.
    >
    > TIA
    >
    > Paul Hammond
    > --
     

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