'$RCSfile: eml-constraint.xsd,v $' Copyright: 1997-2002 Regents of the University of California, University of New Mexico, and Arizona State University Sponsors: National Center for Ecological Analysis and Synthesis and Partnership for Interdisciplinary Studies of Coastal Oceans, University of California Santa Barbara Long-Term Ecological Research Network Office, University of New Mexico Center for Environmental Studies, Arizona State University Other funding: National Science Foundation (see README for details) The David and Lucile Packard Foundation For Details: http://knb.ecoinformatics.org/ '$Author: jones $' '$Date: 2002-12-06 22:23:42 $' '$Revision: 1.45 $' This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA eml-constraint

The eml-constraint schema defines the integrity constraints between entities (e.g., data tables) as they would be maintained in a relational management system. These constraints include primary key constraints, foreign key constraints, unique key constraints, check constraints, and not null constraints, among potential others.

All datasets where there are logical constraints between entities no Relational integrity constraint descriptors Describes the relational integrity constraints of a relational database. The ConstraintType type describes the relational integrity constraints of a relational database. This includes primary keys, foreign keys, unique keys, etc. When an eml-constraint module is created, it should be linked into a dataset using the "triple" element, and all of the entities that are referenced in the constraints should be accessible within that same package. Primary Key The primary key in the entity The primaryKey element declares the primary key in the entity to which the defined constraint pertains. date site Key The set of attributes to which this constraint applies. The key element defines the set of attributes to which this constraint applies. For a primary key or a unique key, the set of attributes must be identifying. For a foreign key, the set of attributes must match an identifying key in the referenced entity. For a 'not null' constraint, the key indicates the attribute which should not be null. site plot Attribute Name Name of an attribute found in the identified entity The attributeReference element is the name of an attribute that can be found in the identified entity. This name will be unique within an entity and specifies that the attribute participates in the key that is being defined. site Unique Key A unique key in the entity The uniqueKey element represents a unique key within the referenced entity. This is different from a primary key in that it does not form any implicit foriegn key relationships to other entities, however it is required to be unique within the entity. date Key The set of attributes to which this constraint applies. The key element defines the set of attributes to which this constraint applies. For a primary key or a unique key, the set of attributes must be identifying. For a foreign key, the set of attributes must match an identifying key in the referenced entity. For a 'not null' constraint, the key indicates the attribute which should not be null. date, site, plot Attribute Name Name of an attribute found in the identified entity The attributeReference element contains the name of an attribute that can be found in the identified entity. This name will be unique within an entity and specifies that the attribute participates in the key that is being defined. site Check Constraint A constraint which checks a conditional clause within an entity. The checkConstraint element defines a constraint which checks a conditional clause within an entity. if site>1 then plot>10 Check Condition An SQL statement or other language implementation of the condition for a check constraint. The checkCondition element defines an SQL statement or other language implementation of the condition for a check constraint. Generally this provides a means for constraining the values within and among entities. (year > 1900 and year < 1990) Language The language that the is used to express or implement the check constraint. The language element declares the language that is used to implement the check constraint. This is typically the name and version of a programming language such as Java, C, Perl, Basic, or other. Sometime it is the name and version of a scriptable analysis system such as SAS, Matlab, R, or SPlus. perl 5.6.1 Foreign Key A foreign key relationship among entities The foreignKey element defines a foreign key relationship among entities which relates this entity to another's primary key. Join Condition A non primary/foreign key join The joinCondition element describes any join of two tables that is not done with a primary/foreign key relationship. JOIN code Key The set of attributes to which a foreign key constraint refers. The referencedKey element defines set of attributes to which a foreign key constraint refers. If the key refers to the primary key in the referenced entity, then the "referencedKey" is optional. For a foreign key, the set of attributes must match an identifying key in the referenced entity. site, plot Attribute Name Name of an attribute found in the identified entity The attributeReference element is the name of an attribute that can be found in the identified entity. This name will be unique within an entity and specifies that the attribute participates in the key that is being defined. Not Null Constraint A constraint that indicates that no null values should be present for an attribute. The notNullConstraint element defines a constraint that indicates that no null values should be present for an attribute in this entity. Key The set of attributes to which this constraint applies. The key element defines the set of attributes to which this constraint applies. For a primary key or a unique key, the set of attributes must be identifying. For a foreign key, the set of attributes must match an identifying key in the referenced entity. For a 'not null' constraint, the key indicates the attribute which should not be null. Attribute Name Name of an attribute found in the identified entity The attributeReference element is the name of an attribute that can be found in the identified entity. This name will be unique within an entity and specifies that the attribute participates in the key that is being defined. Child portion of a cardinality expression Child portion of a cardinality expression Allowed values are positive integers including zero or the string value "many". The CardinalityChildOccurancesType element defines the child portion of a cardinality expression. Allowed values are positive integers including zero or the string value "many". 0,1, 2, 15,many Name of the constraint A meaningfull name of the constraint. The constraintName element is a name which represents a human readible and meaningful name for the constraint. PrimaryKey_birdSurvey Description of the constraint Descibes the purpose of the constraint. The constraintDescription element describes the nature of the constraint. It might be a description of a check condition, or a statement about the composition of a primary key or the nature of the relationship between two database tables or two ascii files. 1.Must be greater than 0 but less than 100 2. "The primary key of the table BIRD_SURVEY is composed of two attributes:speciesCode and observationDate 3. The species name associated with the species code in survey.txt can be found in the file speciesList.txt Key The set of attributes to which this constraint applies. The key element defines the set of attributes to which this constraint applies. For a primary key or a unique key, the set of attributes must be identifying. For a foreign key, the set of attributes must match an identifying key in the referenced entity. For a 'not null' constraint, the key indicates the attribute which should not be null. Attribute Name Name of an attribute found in the identified entity The attributeReference element is the name of an attribute that can be found in the identified entity. This name will be unique within an entity and specifies that the attribute participates in the key that is being defined. Referenced Entity ID The id of the parent-entity in a foreign key constraint. The entityReference element contains the id of the entity to which a foreign key refers, otherwise known as the parent-entity or parent-table. This should be an identifer that matches one of the "identifier" elements for an entity. knb.79.4 Relationship type: Identifying or non-identifying Relationship type: Identifying or non-identifying The relationshipType element defines identifying relationships that propagate from the parent entity's primary key to the child's primary key. Non-identifying relationships propagate the parent's primary key as a non-key attribute of the child entity. felationshipType code Cardinality of the relationship between two entities. Cardinality of the relationship between a parent entity and a child entity. The cardinality element represents a statement of the relationship between parent and child entities. Cardinality is expressed as the ratio of related parent and child entities. Cardinality 1 to N is a specific form of cardinalty in which zero or one parent records are related to a specified number of child records. The cardinality ratio for the parent entity depends on whether the "existence" is mandatory (one or more) or optional (zero to ...). One to many One to 10 Zero or One to Many Parent portion of a 1 to exactly N cardinality Parent portion of a 1 to exactly N cardinality. May have a value of either 0 or 1. The parentOccurences element describes the Parent portion of a 1 to exactly N cardinality. May have a value of either 0 or 1. Value of 0 implies that the "existence" of a child record is optional. Value of 1 implies that the "existence" of a child record is mandatory. One to 10, Zero or One to Many Child portion of the cardinality expression Child portion of a cardinality expression Allowed values are positive integers including zero or the string value "many". The childOccurences element describes the child portion of a cardinality expression Allowed values are positive integers including zero or the string value "many" 2, 15, many