SQL/MX 2.x Installation and Management Guide (G06.24+, H06.03+)

Introduction to SQL/MX Database Management
HP NonStop SQL/MX Installation and Management Guide—523723-004
1-11
SQL/MX Database Object Types
Constraints Constraints protect the integrity of data in a table by
restricting the values in a particular column or set of
columns to those that meet specified conditions. The
SQL/MX constraints are:
•
Not Null, which is a constraint that identifies the column
or columns that cannot contain nulls.
•
Unique, which is a column or table constraint that
identifies the column or set of columns that cannot
contain more than one occurrence of the same value or
set of values.
•
Primary key, which is a column or table constraint that
identifies the column or set of columns that constitute
the primary key for a table. A primary key is also a
unique key.
•
Check, which is a column or table constraint that
identifies the condition that must be satisfied for each
row in a table. Check constraints cannot contain
non-ISO88591 string literals.
•
Referential integrity, which identifies the column or
columns in a table that can contain only values
matching those in a column or set of columns in the
referenced table.
SQL/MP alias A three-part ANSI name that maps to the underlying
Guardian physical name of an SQL/MP object.
Trigger A mechanism that resides in the database and specifies that
when a particular operation—an INSERT, DELETE, or
UPDATE—is performed on a particular table, NonStop
SQL/MX should automatically perform one or more
additional actions.
Partition The portion of a partitioned table or index that resides in a
single physical Guardian file. Multiple partitions can reside
on the same disk volume. A table that has only one partition
is a nonpartitioned table.
Table 1-2. SQL/MX Object Types (page 2 of 2)
SQL/MX Object
Type Description