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Describe integrity constraints?
Integrity Constraints - A database is just as excellent as the information stored in it, and a DBMS must therefore help avoid the entry of incorrect information. An integrity constraint is a condition specified on a database schema and restricts the data that can be stored in an instance of the database. If a database instance satisfies all the integrity constraints specified on the database schema, it is a legal instance. A DBMS enforces integrity constraints, in that it permits only legal instances to be stored within the database.
Integrity constraints are specified and enforced at various times:
When the DBA or end user describes a database schema, he or she specifies the integrity constraints which must carry on any instance of this database. While a database application is run, the DBMS checks for violations and disallows changes to the data in which violate the specified integrity constraints. Several types of integrity constraints can be specified in the relational model, such as, Not Null, Check, Unique, Primary Key, etc.
Increased overheads on update : On the drawbacks side, it will need the system to ensure that all replicas of a relation are consistent. This shows that all the replicas of the rel
Homework chapter 10 no 3
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What are the different integrity constraints in RDBMS? The various integrity constraints in RDBMS are as: Primary Key: primary key is a grouping of one or more attributes
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