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Topic: Integrity constraint

	SAS Data Files : Integrity Constraints
		General constraints, which allow you to restrict the data values that are accepted for the variables in a single data file, such as requiring that the data values for a variable be unique and/or nonmissing, or making the data values in one variable contingent on the data values in another variable.
		A foreign key integrity constraint links the data values of one or more variables in its data file to those of the variables specified in a primary key, and controls the action that can be taken when an attempt is made to update or delete the data values in the primary key.
		When integrity constraints are added to an existing data file, SAS verifies that the data in the variables to which integrity constraints have been assigned conform to the constraints before the integrity constraints are added.
	www.asu.edu /sas/sasdoc/sashtml/lrcon/z0403555.htm (2046 words)

	Data Integrity (Site not responding. Last check: 2007-10-13)
		An integrity constraint is a declarative method of defining a rule for a column of a table.
		A UNIQUE key integrity constraint requires that every value in a column or set of columns (key) be unique--that is, no two rows of a table have duplicate values in a specified column or set of columns.
		In the example in Figure 28-7, the referential integrity constraint ensures that every value in the MGR column of the EMP table corresponds to a value that currently exists in the EMPNO column of the same table, but not necessarily in the same row (that is, every manager must also be an employee).
	www.cs.umbc.edu /help/oracle8/server.815/a67781/c24integ.htm (4646 words)

	Using Integrity Constraints
		When a constraint is disabled, the rule defined by the constraint is not enforced on the data values in the columns included in the constraint; however, the definition of the constraint is retained in the data dictionary.
		This statement is always true when the constraint is enabled; however, the statement may or may not be true when the constraint is disabled because data in violation of the integrity constraint can be in the database.
		To enforce the rules defined by integrity constraints, the constraints should always be enabled; however, in certain situations, it is desirable to disable the integrity constraints of a table temporarily for performance reasons.
	www.cs.uakron.edu /~chan/cs475/DataIntegrity.html (2679 words)

	Constraints and Triggers
		Constraint failures will result in the statement being rolled back - coding an application front end to deal with such errors is generally easier than handling all the business rules in code.
		You can defer checking constraints for validity until the end of the transaction, so the constraint rules don't have to be met until the whole transaction is committed.
		The cost of an integrity constraint is, at most, the same as executing an equivalent SQL statement.
	www.ss64.com /orasyntax/12constraints.html (1073 words)

	Integrity constraint - Computing Reference - eLook.org
		A constraint (rule) that must remain true for a database to preserve integrity.
		Integrity constraints are specified at database creation time and enforced by the database management system.
		Examples from a genealogical database would be that every individual must be their parent's child or that they can have no more than two natural parents.
	www.elook.org /computing/integrity-constraint.htm (55 words)

	Accommodating Site Autonomy in Distributed Constraint Maintenance
		Integrity is specified through a set of integrity constraints, which are assertions or predicates that each legal or consistent database state must satisfy.
		However, the integrity constraint is usually a non-trivial boolean query whose evaluation may be costly in terms of execution time, and repeating these queries after every transaction implies a large overhead for transaction processing.
		In this environment, an integrity constraint must be translated into a set of constraints on those fragments and copies, thus increasing the number of constraints to maintain.
	www.cs.pitt.edu /~panos/idm98/Imported/mazumdar.html (1469 words)

	Maintaining Data Integrity (Site not responding. Last check: 2007-10-13)
		constraints are often combined with other types of integrity constraints to further restrict the values that can exist in specific columns of a table.
		Oracle does not permit declarative referential integrity constraints to be defined across nodes of a distributed database (in other words, a declarative referential integrity constraint on one table cannot specify a foreign key that references a primary or unique key of a remote table).
		Because there is a danger that some constraints might not be re-enabled after a direct path load, you should check the status of the constraint after completing the load to ensure that it was enabled properly.
	www.csee.umbc.edu /help/oracle8/server.815/a68003/01_05dta.htm (5740 words)

	SQL Statements: ALTER TABLE to constraint_clause, 14 of 14 (Site not responding. Last check: 2007-10-13)
		integrity constraint is a rule that restricts the values for one or more columns in a table or an index-organized table.
		Usually, an integrity constraint defined with this syntax can impose rules only on the column in which it is defined.
		To satisfy a referential integrity constraint involving composite keys, either the values of the foreign key columns must match the values of the referenced key columns in a row in the parent table, or the value of at least one of the columns of the foreign key must be null.
	www.usd.edu /oracle/doc/server.817/a85397/state14a.htm (3635 words)

	Maintaining Data Integrity Through Constraints (Site not responding. Last check: 2007-10-13)
		To enforce this rule without integrity constraints, you can use a trigger to query the department table and test that each new employee's department is valid.
		The order in which the constraints are evaluated is not defined, so be careful not to rely on the order or to define multiple constraints that conflict with each other.
		The assertion may or may not be true when the constraint is disabled, because data that violates the integrity constraint can be in the database.
	www.ucs.louisiana.edu /~oracle9i/appdev.901/a88876/adg05itg.htm (5365 words)

	Grefen, P.; Widom, J.: Integrity Constraint Checking in Federated Databases
		A federated database is comprised of multiple interconnected databases that cooperate in an autonomous fashion.
		Global integrity constraints are very useful in federated databases, but the lack of global queries, global transaction mechanisms, and global concurrency control renders traditional constraint management techniques inapplicable.
		This paper presents a threefold contribution to integrity constraint checking in federated databases: (1) The problem of constraint checking in a federated database environment is clearly formulated.
	dbpubs.stanford.edu:8090 /pub/1996-48 (258 words)

	DBMS - August 1996 - Server Side (Site not responding. Last check: 2007-10-13)
		Remember that integrity constraints ensure that the data in a database is correct and accurate (I covered referential-integrity constraints in last month's column).
		You use a column integrity constraint to further refine or restrict the definition of a generic domain for the specific context of the table in which the domain is used.
		Another well-known column constraint is the not null, which is used to specify that a particular column may not take the undefined null value.
	www.dbmsmag.com /9608d17.html (3134 words)

	Joel on Software - Integrity constraint validation
		You're quite free to implement your own integrity checks prior to trying to modify data, of course -- they'll be slower than letting the database do them, and you'll have to be careful about handling consistency issues ("It passed my check but then the data changed between the check and the attempted insert!").
		Clearly the fact that you are having such issues with constraint errors bubbling up to the UI implies that developers ARE NOT SMART ENOUGH or else their checks should have caught the issues before the database layer or their code should be able to show friendly error messages.
		Database integrity checks are like exceptions - they should be a last ditch protection mechanism to _ensure_ that the data is clean (because the database and its data, in almost every project, is the longest living, most important part of the project), however they should almost never be triggered.
	discuss.joelonsoftware.com /?joel.3.230257 (1883 words)

	Database P&D Online
		A referential integrity (RI) constraint specifies that the value of the specified column in every row of the referencing table appears as the value of a specified column in a row of the referenced column.
		The temporal analogue of a nontemporal referential integrity constraint is the sequenced constraint: "At each point in time, each incumbent's PCN is valid at that time." This applies the intuition of referential integrity to time-varying information.
		As with duplicates, stating a sequenced referential integrity constraint in English is natural, but stating it in SQL is challenging.
	www.dbpd.com /vault/9810/temporal.html (2580 words)

	Fileid=Maketabs
		Referential Integrity does permit foreign keys to have null values; however, this is uncommon.
		integrity constraint on a column or set of columns requires that a specified condition be true or unknown for every row of the table.
		Each constraint is named using prefixes to denote the type of constraint.
	www.siue.edu /~dbock/cmis564/maketabs.htm (1166 words)

	Integrity Constraints in Temporal Relational Databases
		The article addresses the key issues of integrity constraints in temporal data within the relational framework.
		We extend the traditional integrity constraints to the temporal domain.
		The time component of a temporal integrity constraint limits the attribute values to the lifespan of an object (tuple) and it is peculiar to temporal data only.
	csdl2.computer.org /persagen/DLAbsToc.jsp?resourcePath=/dl/proceedings/&toc=comp/proceedings/itcc/2004/2108/02/2108toc.xml&DOI=10.1109/ITCC.2004.1286696 (217 words)

	CS145 - Autumn 96/97
		We observed that the higher-numbered types of constraints tend to be more general than the lower-numbered types, and in fact many of the lower-numbered types can be expressed using the higher-numbered types instead.
		Include only referential integrity constraints that involve two different relations, i.e., the foreign key is in one relation and the primary key is in another.
		If your PDA has no natural referential integrity constraints, then it probably is either far simpler than we asked for, or a very poor design.
	www-db.stanford.edu /~ullman/fcdb/aut96/hw5.html (1421 words)

	Further Improvement on Integrity Constraint Checking for Stratifiable Deductive Databases - Lee, Ling (ResearchIndex)
		Abstract: Integrity constraint checking for stratifiable deductive databases has been studied by many authors.
		However, most of these methods may perform unnecessary checking if the update is irrelevant to the constraints.
		1 Integrity constraint in deductive databases (context) - Kowalski, Sadri et al.
	citeseer.ist.psu.edu /lee96further.html (514 words)

	ACID Definition \| Computer Dictionary \| Define meaning of ACID (Site not responding. Last check: 2007-10-13)
		This means that a transaction can't break the rules, or integrity constraints, of the database.
		If an integrity constraint states that all accounts must have a positive balance, then any transaction violating this rule will be aborted.
		This means it will survive system failure, and that the database system has checked the integrity constraints and won't need to abort the transaction.
	www.cpupedia.com /definition/acid.aspx (576 words)

	Grefen, P.; Widom, J.: Protocols for Integrity Constraint Checking in Federated Databases
		A federated database is comprised of multiple interconnected database systems that primarily operate independently but cooperate to a certain extent.
		Global integrity constraints can be very useful in federated databases, but the lack of global queries, global transaction mechanisms, and global concurrency control renders traditional constraint management techniques inapplicable.
		Thus, our work yields a suite of options from which a protocol can be chosen to suit the system capabilities and integrity requirements of a particular federated database environment.
	dbpubs.stanford.edu:8090 /pub/1994-23 (326 words)

	[No title]
		= 4.00) The domain has a constraint that ensures that the hourly-wage is greater than 4.00 The clause constraint value-test is optional.
		If a cascading update to delete causes a constraint violation that cannot be handled by a further cascading operation, the system aborts the transaction.
		As a result, all the changes caused by the transaction and its cascading actions are undone¡,ÌZPkó¨Cascading Actions in SQL¨\Referential integrity is only checked at the end of a transaction Intermediate steps are allowed to violate referential integrity provided later steps remove the violation Otherwise it would be impossible to create some database states, e.g.
	www.cbu.edu /~yanushka/db/c6.ppt (1341 words)

	CIKM 1995: 82-89
		Since parallelism is a promising strategy for improving efficiency in database systems we apply parallelism to integrity constraint checking.
		The extensions of the algebra are due to the complexity of the integrity constraints which come from a real application.
		Finally, measurements performed with a parallel main-memory database demonstrate the processing costs that can be achieved by parallel integrity constraint evaluation.
	www.vldb.org /dblp/db/conf/cikm/HerzogS95.html (644 words)

	Efficient and Complete Tests for Database Integrity Constraint Checking - Gupta, Sagiv, Ullman, Widom (ResearchIndex)
		Abstract: this paper we focus our discussion on constraints expressed as conjunctive queries with arithmetic comparisons, we suppose the only accessible relation is the updated relation, and we consider updates that are insertions of a single tuple.
		The general form of a conjunctive query constraint is: (Update)
		Efficient andcomplete tests for database integrity constraint checking.
	citeseer.ist.psu.edu /gupta94efficient.html (531 words)

	DBAsupport.com Forums - ORA-02291: integrity constraint (S3034595.FKPOSITION_ID) violated - parent key not fo
		Rapid and Reliable System and Data Recovery: Learn to reliably perform bare metal recovery within minutes.
		ORA-02291: integrity constraint (S3034595.FKPOSITION_ID) violated - parent key not fo
		SQL> alter table job disable constraint position_id; alter table job disable constraint position_id * ERROR at line 1: ORA-02431: cannot disable constraint (POSITION_ID) - no such constraint SQL> alter table job disable constraint fkposition_id; Table altered.
	www.dbasupport.com /forums/showthread.php?t=44612 (430 words)

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