TurboIMAGE/XL Database Management System Reference Manual (30391-90012)

182 Chapter5
TurboIMAGE/XL Library Procedures
DBFIND
3-4 version number. Must be numeric zero, or an error is
returned.
5-6 The size (in bytes) of argument1 (not including these two
bytes) for search types =, <, <=, >, >=, @
c , PK.
7-8 The size (in bytes) of argument2 (not including these two
bytes) for the search type [ ]. Must be numeric zero for
other search types, or an error is returned.
9... 9+n-1 Argument1. The n bytes of argument data (for example,
for an X10 field,
n = 10).
9+n... 9+n+m-1 Argument2. For search-type [ ] only. The
m bytes of the
second argument's data (for example, for an X10 field,
m =
10,
n must match m ).
If a wildcard character is present in the argument(s), the wildcard will be
considered as part of the value for these B-Tree search types: = , < , <=,
> , >=, [ ], or PK on ASCII types.
If your database is enabled for third-party indexing (TPI), refer to your
vendor documentation for information on DBFIND arguments. The section
on DBUTIL in chapter 8 of this book has a brief description of the TPI
option.
Discussion
When the DBFIND is not for a B-Tree index, the current values of chain count, backward
pointer, and forward pointer for the detail data set referenced in dset are replaced by the
corresponding value from the chain head.
A current path number, which is maintained internally, is set to the new path number and
the current record number for the data set is set to zero. Refer to chapter 10 for further
information about chain heads and internally maintained data set information.
Although a master set entry with the specified key item value exists, the data set chain
may be empty.
For B-Tree DBFINDs, there could be multiple qualified chain heads. The chained access
could traverse multiple chains, referred to as super-chain. When using modes 1 or 4 for
B-Tree DBFINDs, the qualified chain heads are retrieved, and the chain count becomes a
cumulative chain count of the super-chain. The record number of last entry is obtained
from the last entry of the last chain and the record number of the first entry is obtained
from the first entry of the first chain. For modes 21 and 24, the qualified chain-heads are
retrieved only during DBGETs, and hence, inaccurate chain counts and record numbers of
last entry and first entry are returned for DBFIND.
For B-Tree DBFINDs:
• Can be used both for master data set and detail data sets.
• Allows wildcard search, relational operators, as well as range search.
• DBFIND mode 1 will result in a B-Tree wildcard search, if all of the following are true: