Richard, Carlos, Simcha and Nigel,
Thank you all for your answers on this matter. When I read Simcha's mail, it
hit me like a hammer!
That was what I was looking for! BUT: I have to see, that this creates way
to much overhead, as I have to use INNER JOIN instead of LEFT JOIN, or an
equvalent subquery.
I'm currently testing with temporary tables to filter the data before going
into the real query.
As this is not a real project, just me testing the pros and cons of speed
versus flexibility of exactly this table structure, there is no need to
restructure the tables.
I use 30,000 images as sample data, 7 attributes each.
What I have for the images is 3 tables.
table picture
pid(primary): the id of the picture
uid(index): the user id, to whom the image belongs
table picture_attribute
aid(primary): the id of the attribute
name(index): a name for that attribute e.g. fsize
table picture_attrib_rel (unique over pid,aid - to avoid the same attribute
twice
pid(index): the picture, this row belongs to
aid(index): the type of attribute this row describes
val_int(NULL): a field for integer values |
val_vc(NULL): a field for string values | my class decides
wich of these value types to use,
the other is NULL
My class emulates a foreign_key behavior on aid between picture_attribute
and picture_attrib_rel.
THANK YOU ALL!!
Regards,
Jan
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