Re: [libreoffice-users] Re: LO 4.0: intrinsic database: relations only between primaries keys?

Dan,
This is good!  It is a good start on an introduction to databases for 
newbies.
It should be put in the Base manual?
Girvin Herr

Dan Lewis wrote:
<snip>
>       Some basics about creating a database:
> 1) You begin with data that you want to use for some purpose or purposes.
> 2) Then you design the database to organize this data so that it will 
> be useful.
>
> For example: an address database:
>      In the beginning, the database consists of information such as 
> names, addresses, email address, phone numbers, etc.
>      The first thing you would want to do is to organize this data so 
> that a name is linked to its address, its email address, its phone 
> numbers, etc. Now you have rows of data, each one of them containing 
> information about a single person (a relationship exists between the 
> data for each row). Each of these pieces of information is a field.
>      If you look at these rows, you will see that they also contain 
> some things in common. Several rows can contain data about your 
> friends, others are about your relatives, and others are about 
> companies you do business with. You probably know of other 
> possibilities. So, these rows can be organized into groups based upon 
> what they have in common. (This too is a relationship.)
>      The next thing you should do is to further organize these rows in 
> each one of these groups to make them more useful. You could form a 
> table using these as the column headings: name, address, email 
> address, and phone number. ( Now you have a table for each group of 
> rows. So, if you want data about a particular contact, you can go to 
> the table that contains it. If you want to look at the data for a 
> relative, you go to the table containing all of your relatives.
>      This is basically how a flat database is created. Relational 
> databases begin in the same way.
>      At this point, each of these tables are checked to see whether 
> they are "normal" or not. For example, a contact is likely to have 
> multiple phone numbers or other possible multiple entries. Each of 
> these have something in common (another relationship). We can remove 
> the field containing multiple entries forming a new table. To keep the 
> relationship between this new table with the original table, we create 
> a primary-foreign key pair (the primary key is for the new table, and 
> the foreign key is added to the original table in place of the fields 
> we removed.) This is what is done to make a table "first normal form".
>      There are several levels of a table being normal: "first normal 
> form" to "fourth normal form" and beyond. "Fourth normal form" is 
> considered to be the standard against which a table should be judged.
>      The point being that we do not create tables with their fields 
> and then define the relationship between them. We begin the the fields 
> that we know we will need, combine the fields based upon relationships 
> between data, and combine the fields into tables based upon 
> relationships between the fields. The the tables are normalized up to 
> "fourth normal form" creating new tables and modifying the old ones. 
> Primary-foreign key pairs are used to define the relationship of the 
> new tables and the modified old table from which the new table came.
>      Hopefully this will help some.
>
> --Dan

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