Neoview SQL Reference Manual (R2.4)

Null and Expression Evaluation Comparison
ResultConditionExpression Type
For AND, the result is null. For OR, the
result is true if the other operand is
true, or null if the other operand is null
or false. For NOT, the result is null.
Either operand is null.Boolean operators (AND, OR, NOT)
The result is null.Either or both operands are null.Arithmetic operators
The result is true.The operand is null.NULL predicate
The result is null if set is empty.Some rows have null columns.The
function is evaluated after eliminating
nulls.
Aggregate (or set) functions (except
COUNT)
The result is the number of rows in the
table whether or not the rows are null.
The function does not eliminate nulls.COUNT(*)
The result is zero if set is empty.The function is evaluated after
eliminating nulls.
COUNT COUNT DISTINCT
The result is null.Either operand is null.Comparison: =, <>, <, >, <=, >=, LIKE
The result is null if all of the
expressions are null.
Some expressions in the IN value list
are null.
IN predicate
The result is null.No rows are returned.Subquery
Partitions
Typically, there is a one-to-one correspondence between a table definition and a physical file.
However, large tables or tables with special performance requirements might require partitioning
into multiple physical files.
A partition is the part of a table or index that resides on a single disk volume. Each table or index
consists of at least one partition. A nonpartitioned table or index consists of exactly one partition.
A partitioned table or index consists of more than one partition.
You create partitions by using the PARTITION clause in a CREATE TABLE or CREATE INDEX
statement or a MODIFY statement. [IS THIS TRUE FOR NEO?]
For more information, see “CREATE TABLE Statement” (page 70), “CREATE INDEX Statement”
(page 59), and “ALTER VIEW Statement” (page 53).
Automatically Creating Partitions
When creating a table, users can specify that the table is not partitioned using the NO PARTITION
clause. The default is for the table to be partitioned.
Users may also specify the MAX TABLE SIZE clause that will be used to decide on the table
extent sizes. If this option is not specified Neoview SQL will decide. If the table is partitioned
then the table is partitioned across all the disk volumes on the system.
266 SQL Language Elements