Apple Newton Programmer’s Newton 2.0 (for Newton 2.0) - Manual (Page 445)

C H A P T E R 1 1
Data Storage and Retrieval
About Data Storage on Newton Devices 11-13
exclusive forms of the same endrange selector; for example, a single query spec
cannot specify both a
beginKey value and a beginExclKey value.
Another important point to understand is that there is only one beginKey or
beginExclKey value, and only one endKey or endExclKey value associated
with any query and the cursor it returns.
Figure 11-4 Using beginExclKey and endExclKey values to specify
a subrange
Each beginKey , beginExclKey , endKey , or endExclKey specification
evaluates to a single value that has a unique position in the sorted index key data.
This position marks one end of the range over which the cursor iterates. The cursor
never moves to a position outside the range specified by these keys.
If any endrange selectors are defined for a query, the relationship of the cursor’s
entries to the endrange selectors may be summarized as follows:
entry > beginExclKey
entry ≥ beginKey
entry ≤ endKey
entry < endExclKey
You can think of these values as being used by the system in an inequality
expression to specify the range of the cursor; for example,
beginKey ≥ entry < endExclKey
Note that if a valid entry is not found at the key value specified for an endrange
selector, the cursor is positioned on the nearest entry in index key order that falls
within the range specified by the endrange selectors. For example, if a valid entry is
not found at the key value specified for a
beginKey or beginExclKey value, the
Ascending key order
Descending key order
subrange of index key values
3 4 5
beginExclKey endExclKey