BUILDER DATABASE FUNCTIONS


The Builder Database functions are a flexible and easy to use set of
Clipper UDFs designed to add/change/delete database records.


One of the features that make them so easy to use is the ability to
add or change databases one record at a time.  This is an advance
over the normal xBase style of one field at a time database I/O.

The way this is achieved is to create a STATIC array of field values for
every database in your application.  A corresponding manifest constant
entry is made in a Header (.ch) file for every database field in your
application.  The manifest constant is created by prefixing the field name
with an alphabetic character.  For example, the database field CITY might
become the manifest constant 'ACITY'.  'ACITY' would then get translated by
the Clipper preprocessor to an array element, like 'aCity[1]'.  Therefore
the aCity file wide STATIC array is equal to one record in the Cities
database.  This method of using manifest constants instead of the array
syntax provides both readable source code and efficient access to database
data.

The Builder Save_It() function requires four parameters in order to
Add/Change/Delete/ or Recall a database record.  When adding a record
you can (optionally) use the deleted records of your database as
"Add Space" when using the Save_It() function.  That way recycling
your deleted records instead of APPENDing BLANK to add a record.
Using this feature requires that SET DELETED ON is active (Builder
default) and that each database to use this feature has an open
index created like: INDEX ON IF(DELE(),"*"," ") TO ...  This uses one
valuable file handle per database; but the ease of maintaining data
integrity, NEVER-EVER having to PACK these databases, and maintaining
top performance makes this an excellent solution for network database
systems.

Note that using Save_It() to delete a database record will delete in
a cascade fashion all child related records also.  Cascade deleting
will only occur if the database has active RELATIONs set.  All Builder
File Mainteneance and TBrowses that allow record deletions call Save_It()
and will, therefore, have cascading deletes.

Other Builder database functions do your file maintenance chores for you,
including maintaining related databases.  Move field data to memory with
DbStor(), Browse databases with Plist().  Use Fld_Repl() instead of
REPLACE when only a few fields need to be updated.  Fld_Repl() locks and
unlocks records when used on a network.


Also see the following functions in the Builder library documentation:
  DbStor()      - Store database fields to an array.
  Fil_Lock()    - Lock an entire database.

The following functions are in the Builder library, but are used
internally only and should not be required in any other way.
  DbRepl()      - Write a database record from an array.
  Add_Rec()     - Append a Database Record, Network Aware
  Net_Use()     - Called by Open_Fil() after error testing.
                  Opens a database, used in Summer '87 only.
  Rec_Lock()    - Lock a database record.

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