Subject | Re: [firebird-support] design question |
---|---|
Author | Jacqui Caren |
Post date | 2004-08-20T11:24:50Z |
Lester Caine wrote:
Another approach is discrimiated values.
i.e.
name vachar(32),
vtype char(3),
val_i integer,
val_v varchar(200)
val_lv varchar(...)
you use the value of vtype to determine which field (or detail table)
has the value you require - for large number of data types
detail tables may be used - SS7 has *nasty* record len limits :-)
Messy, but can be usefull.
Jacqui
> Planles wrote:Because no one else mentioned it :-)
>
>
>>Is there any problem to be expected, if there number of columns in one table
>>is growing and growing ?
>>Is there any limit, how many columns (fields) per table can be ?
>
>
> Maximum row size 64kb, but there is no problem having multiple tables
> with different groups of these fields.
> There are many things that you may want to include in a query so a
> single record table is not a problem.
Another approach is discrimiated values.
i.e.
name vachar(32),
vtype char(3),
val_i integer,
val_v varchar(200)
val_lv varchar(...)
you use the value of vtype to determine which field (or detail table)
has the value you require - for large number of data types
detail tables may be used - SS7 has *nasty* record len limits :-)
Messy, but can be usefull.
Jacqui