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Are Databases Huge?
Message
Information générale
Forum:
Visual FoxPro
Catégorie:
Base de données, Tables, Vues, Index et syntaxe SQL
Divers
Thread ID:
00538451
Message ID:
00538517
Vues:
8
>I am moving from FPW26 to Visual FoxPro 6. I am considering making a database as opposed to using free tables, but am concerned that in doing so I will end up with a single huge file (like Access!) instead of my hundreds of much more easily handled and controlled free tables. Will I indeed end up with a 100MB database file, or will I have a small database file which simply communicates with the 100MB of data? Also, will I be able to open up a single table within a database AS IF it it were a free table once I change? THANKS SO MUCH.

When you add a table to a database it's header is modified with linking information, so that if you open the table it opens the database too. Databases are the only way you can get referiential integrity, cascade deletes, etc..., and where you can store certain procedures besides those relating to inserting, updating and deleting. Permenant local and remote views are stored in the database too.

If you want to remove a table from a database without deleting it VFP gives you that option. Sometimes, databases and/or tables crash and the linking information is destroyed. There are way to fix that problem too.

One word of caution... the database gives you the ability to use field names that are longer than 10 characters. If you use that feature in a table, MAKE SURE that the FIRST 10 characters of each fieldname in a table are unique. I made the mistake, when I was learning VFP, of using the tablename as the first part of each fieldname. Well, it seems that a table name was over 10 characters in length and I began each field in that table with the table name plus some addition identifying information. When the database crashed the table was disconnected and the links between the long field names and the system maintained actual names were broken. All fields that began with the same 10 characters were deleted, except for the first one. Big mess.

Backup, backup, backup.
Nebraska Dept of Revenue
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