HP 3000 Manuals HP 3000 Manuals
GENERIC KEYS
NLS collating sequences differ from the USASCII collating, and the
differences must be considered when performing generic key searches.
Refer to the Native Language Support Reference Manual (32414-90001) for
more information.
The description of a generic key search in a KSAM file with a native
language attribute is presented from an application point of view
Keys matching a certain generic key may not be in consecutive order in
the key file because the keys are sorted according to a native language
collating sequence. The key sequence in Figure F-3 illustrates this with
a French KSAM file; keylength is 4, the generic key length is 2. The
partial key "aa" appears in nonconsecutive keys (with a result of 0 in
the last column of the figure). Records containing partial keys (such as
"AA" or "Aa"0 are intermixed according to the French collating sequence.
These keys have a result of 1 listed.
If a generic key search is performed in a KSAM file with a language
attribute other than NATIVE-3000, the application program must determine
whether the retrieved record matches the generic key and, even if it does
not, whether subsequence records might still match it.
The codes returned by NLKEYCOMPARE are shown in Figure F-2.
Refer to the Native Language Support Reference Manual (32414-90001) for a
complete discussion of the NLKEYCOMPARE intrinsic.
Figure F-2. Results Returned By The NLKEYCOMPARE Intrinsic
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| |
| RESULT MEANING |
| |
| 0 The retrieved key matches the generic key exactly. |
| |
| 1 The retrieved key does not match the generic key. |
| Uppercase/lowercase priority or accent priority is different. |
| |
| 2 The retrieved key value is less than the generic key. It precedes |
| the designated key in the collating sequence. |
| |
| 3 The retrieved key is greater than the generic key. |
| |
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The generic key search sequence is:
1. After FFINDBYKEY has been called with >= as relational
operator(relop), the logical record pointer points to the data
records indicated by the arrow labeled "Case 2".
2. The subsequent FREAD call will retrieve the data record. When the
partial key "AA" is compared to the generic key "aa" they are
found to be different.
This comparison is done by calling the intrinsic NLKEYCOMPARE
using the generic key and the key found in the record. The result
returned by NLKEYCOMPARE tells the application whether the FREAD
delivered a record:
a. Before the desired range (result 2).
b. In the desired range with an uppercase/lowercase or accent
priority difference (result 1).
c. With an exact match (result 0).
d. After the desired range (result 3).
3. To get all records whose key match the generic key exactly, the
FREAD calls and subsequent NLKEYCOMPARE call should continue until
a result of 3 is returned.
When performing a generic key search in a KSAM file with a native
language attribute other than NATIVE-3000 use the NLKEYCOMPARE intrinsic
to compare partial keys and generic keys.
Refer to the Native Language Support Reference Manual (32414-90001) for
examples of generic key searches in KSAM files with native language
attributes.
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|Key length: 4 |
| |
|Language: FRENCH (only USASCII characters are used in the example). |
| |
|Desired records are all records whose record key starts with "aa" |
|(generic key = "aa", length = 2) . |
| |
| |
| Pointer Key NLKEYCOMPARE Result |
| Position Value ("aa" Compared to Key) |
| |
|--------------------------------------------------------------------------------------|
| |
| Case 1---> A 2 |
| |
| a 2 |
| |
| Case 2---> AA 1 |
| |
| Aa 1 |
| |
| aA 1 |
| |
| aa 0 |
| |
| AAA 1 |
| |
| aaa 0 |
| |
| AAAA 1 |
| |
| AAAa 1 |
| |
| AAaa 1 |
| |
| AaAa 1 |
| |
| AaaA 1 |
| |
| Aaaa 1 |
| |
| aAAA 1 |
| |
| aAAa 1 |
| |
| aAaA 1 |
| |
| aaAA 0 |
| |
| aaaA 0 |
| |
| aaaa 0 |
| |
| Case 3---> Baaa 3 |
| |
| baaa 3 |
| |
| |
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Figure F-3. Generic Key Searches
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|Case: |
| |
| |
| 1. FREAD starting at the beginning of the file. |
| |
| 2. FFINDBYKEY with relational operator = or >= and subsequent |
| FREAD calls. |
| |
| 3. FFINDBYKEY with relational operator > and subsequent FREAD |
| calls. |
| |
|Key Value: Key values in ascending sequence. |
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Figure F-4. Generic Key Searches