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in the table design I have declared datalength nvarchar as 50 but the query show 100 - why?

Posted on 2011-03-20
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Last Modified: 2012-05-11
I am using ms sql 8
in the table design, I have declared
Job      nvarchar(50)      Checked


SELECT table_name=sysobjects.name,
         column_name=syscolumns.name,
         datatype=systypes.name,
         length=syscolumns.length
    FROM sysobjects
    JOIN syscolumns ON sysobjects.id = syscolumns.id
    JOIN systypes ON syscolumns.xtype=systypes.xtype
   WHERE sysobjects.xtype='U' and sysobjects.name='AceData' and syscolumns.name='Type'
ORDER BY sysobjects.name,syscolumns.colid

table_name      column_name      datatype      length
AceData      Type      nvarchar      100
AceData      Type      sysname      100
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Question by:goodk
4 Comments
 
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Expert Comment

by:Prafulla Maharjan
ID: 35175692
In vharchar u declared u declared as 50
but in the table width u just check whether u have 100 or not.. It is also depends on the table on the  width...
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Accepted Solution

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ssisworo earned 500 total points
ID: 35175836
use the length of the column "syscolumns.prec" information,
whereas "syscolumns.length" column is used to measure the amount of storage.

SELECT table_name=sysobjects.name,
         column_name=syscolumns.name,
         datatype=systypes.name,
         length=syscolumns.prec
    FROM sysobjects
    JOIN syscolumns ON sysobjects.id = syscolumns.id
    JOIN systypes ON syscolumns.xtype=systypes.xtype
   WHERE sysobjects.xtype='U' and sysobjects.name='AceData'
ORDER BY sysobjects.name,syscolumns.colid
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LVL 50

Expert Comment

by:Lowfatspread
ID: 35179166
nvarchar uses 2 bytes per character of storage...

so your nvarchar(50)  will actually use 100 bytes to store the data

datalength(columnname)  gives the numbers of bytes used for data by a column/expression

length(columnname) gives the number of characters used for data by the column/expression ignoring trailing spaces...

a "Varchar" datatype will also typically use and additional 2bytes to store the lenght of the data its is storing.. which is not included in the "displayed" values

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Author Closing Comment

by:goodk
ID: 35181555
works like a charm - thanks
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