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hasanali00
Posting Yak Master
207 Posts |
 Posted - 2004-11-05 : 07:01:56
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| How important is the 'Length' of a table field.Does it mean that this field cannot contain data more than the lenght of this field.What happens, if I try to insert data into this field which is more than the length. When designing a table, does it matter if I create large field lengths. e.g does it affect performace...etckind regards |
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AndrewMurphy
Master Smack Fu Yak Hacker
2916 Posts |
Posted - 2004-11-05 : 07:22:39
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| in short.1. very2. yes3. chop off and discard the extra data4. it can....unused space still has to be traversed to get to populated data....it also costs money. |
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Kristen
Test
22859 Posts |
Posted - 2004-11-05 : 07:59:58
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| Errrmmm ... I think 3 is error "String or binary data would be truncated"4 if varchar then there is no wasted space is there?Kristen |
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robvolk
Most Valuable Yak
15732 Posts |
Posted - 2004-11-05 : 08:08:24
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| If you get "String or binary data would be truncated" then the row is not inserted. A multi-row operation would fail and no rows would be inserted:create table #duh(a varchar(4) not null)insert #duh select '123' union allselect '1234' union allselect '12345'select * from #duhdrop table #duhVarchar won't store more data than the length of the value, but it may still "waste" some space. If you update a varchar column from 1000 bytes to 500, that now-empty space will not be reclaimed or reused on the data page unless the table was reindexed (even then it may not be reused) |
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Kristen
Test
22859 Posts |
Posted - 2004-11-05 : 08:33:04
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| "update a varchar column from 1000 bytes to 500"Good point, hadn't thought of that.Kristen |
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hasanali00
Posting Yak Master
207 Posts |
Posted - 2004-11-05 : 08:56:45
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| Any difference between nvarchar & charvar.I always tend to use nvarchar |
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AndrewMurphy
Master Smack Fu Yak Hacker
2916 Posts |
Posted - 2004-11-05 : 09:22:05
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| the 'n' versions are only worthwhile/needed if you have some form of internationalisation to worry about, particularly support for asian and/or arabic character sets.otherwise for plain old english data, you would double the size of the dataspace compared to the 'non-n' versions of the columns. |
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Table Field Length