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Use bit data type for boolean?

  • April 15, 2005 at 8:11 am

    #85532

    A few things here regarding using the BIT data type for booleans.

    1) Storage Space? I would guess that SL server still has to use at least a byte - or prolly more to store a "bit".  This applis to disk and memory.

    2) I prefer using a char(1) and setting it to 'Y' or 'N'.  Everyone knows for sure, immediately, what the data means.

    Does anyone know the facts the behind storage of bits?

    Flame me if you want regarding my use of chars.

    - B

     

  • April 15, 2005 at 8:25 am

    #552916

    Yes, 1 byte is always needed to store bit columns, even if there is only one column. However, if there are more than one bit column on a table they will share that byte, so if you have eight bit columns the storage needed will still be 1 byte.

    --
    Chris Hedgate http://www.hedgate.net/
    Contributor to the Best of SQL Server Central volumes
    Articles: http://www.sqlservercentral.com/columnists/chedgate/

  • April 15, 2005 at 8:32 am

    #552917

    Thanks - pretty much what I figured.

    What do you recommend using for bools?

  • April 15, 2005 at 9:50 am

    #552943

    For what its worth, my recommendation is to use the BIT datatype.  It provides the built in limitation of valid values and when looking at the column definition it is instantly clear that its purpose is as an on/off true/false indicator.

    Just my 2 cents.

     

  • April 15, 2005 at 10:08 am

    #552951

    But..

    If you are planning to use many BIT columns and the table can be large guess what you can't index it it is better then to group them and use bit manipulation functions to query the indexed column(s)

     


    * Noel

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