The RDB$RELATION_CONSTRAINTS system table lists all table-
specific constraints. The following table provides information
on the columns of the RDB$RELATION_CONSTRAINTS system table.
Data
Column Name Type Summary Description
RDB$CONSTRAINT_MATCH_TYPE integer The match type associated
with a referential
integrity table-specific
constraint. This column is
reserved for future use.
The value is always 0.
RDB$CONSTRAINT_NAME char(31) The name of the constraint
defined by the table
specified by RDB$RELATION_
NAME.
The value in this column
equates to a value for the
same column in the
RDB$CONSTRAINTS system
table.
RDB$CONSTRAINT_SOURCE list This text string contains
of byte the source of the
varying constraint from the table
definition.
RDB$CONSTRAINT_TYPE integer The type of table-specific
constraint defined. The
values are shown in the
RDB$CONSTRAINT_TYPE Help
topic.
RDB$ERASE_ACTION integer The type of referential
integrity erase action
specified. This column is
reserved for future use.
The value is always 0.
RDB$FIELD_NAME char(31) The name of the column
for which a column-level,
table-specific constraint
is defined. The column is
blank for a table-level
constraint.
RDB$FLAGS integer Flags.
RDB$MODIFY_ACTION integer The type of referential
integrity modify action
specified. This column is
reserved for future use.
The value is always 0.
RDB$REFD_CONSTRAINT_NAME char(31) The name of the unique or
primary key constraint
referred to by a
referential integrity
foreign key constraint.
If the constraint is
not a referential
integrity constraint or
no referential integrity
constraint was specified,
this column will be
null. Otherwise, the
value in this column
will equate to a value
for the same columns in
the RDB$CONSTRAINTS and
RDB$RELATION_CONSTRAINT_
FLDS system tables.
This column is used to
determine the foreign key
referenced table name and
referenced column names.
RDB$RELATION_NAME char(31) The name of the table
on which the specified
constraint is defined.
The value in this column
equates to a value for
the same column in the
RDB$RELATIONS system table.
RDB$SECURITY_CLASS char(20) Reserved for future use.
1 – RDB$FLAGS
Represents flags for RDB$RELATION_CONSTRAINTS system table.
Bit
Position Description
0 This is SQL standard UNIQUE constraint which allows
unique values and ignores NULL.
2 – RDB$CONSTRAINT_TYPE
The following table lists the values for the RDB$CONSTRAINT_TYPE
column.
Value Symbol Meaning
1 RDB$K_CON_CONDITION Requires conditional expression
constraint.
2 RDB$K_CON_PRIMARY_KEY Primary key constraint.
3 RDB$K_CON_REFERENTIAL Referential (foreign key)
constraint.
4 RDB$K_CON_UNIQUE Unique constraint.
5 Reserved for future use.
6 RDB$K_CON_NOT_NULL Not null (missing) constraint.