Integrity constraints in a database management system (DBMS) help to maintain the quality and consistency of data. They also help to prevent unauthorized access and optimize performance.
There are four main types of integrity constraints that a database can enforce, which is the answer of this question: Which of the Following is Not an Integrity Constraint. These are: CHECK, FOREIGN KEY, NON-NULL and UNIQUE.
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Referential integrity
Referential integrity is a database feature that ensures that references between two tables are valid. This prevents logical corruption of data by ensuring that each row in one table must be able to uniquely identify each record in the other.
Referral integrity is enforced by working with primary and foreign keys in relational databases. It is important to understand this feature because it can help prevent records from being lost in the database, or strange results appearing in reports.
For example, consider a table that stores basic customer and account holder information. The table contains a foreign key to a related table that holds more detailed data. If a record is deleted in the main table, all the corresponding records in the related table will also be removed to maintain referential integrity.
The main table, called the CUSTOMER_MASTER table, contains a primary key that uniquely identifies customers, as shown in screen 1. This table is a parent key to the related table, called the ACCOUNTS_MASTER table.
Another table, called the Orders table, contains a primary key that uniquely uniquely identifies orders. This table is a child table to the Orders table.
In this case, a referential integrity constraint requires that the order_id column of the Orders table must match a valid order_id in the customer_id column of the Customer table. The order_id must be a unique combination of the customer ID and a part number to uniquely identify an order.
Alternatively, a referential integrity constraint can require that the part number column in the Parts table must match a valid part_number in the OrderDetails table. The part number must be a unique combination of the order_id and a quantity to uniquely identify a part.
The referenced table must contain a foreign key that consists of the same number of columns as the foreign key in the parent table. The table must also have a corresponding data type.
In most relational databases, declarative referential integrity is used to ensure that all references between tables are valid. However, some types of foreign keys may violate referential integrity. Fortunately, most of these violations can be prevented by the database using a choice of three different methods. These include disallowing, cascading, or setting the foreign key to null.
Non-null integrity
In a relational database, integrity constraints are a set of rules that a database administrator or application developer can specify. These rules apply to all data in the table and ensure that the values are consistent with one another.
There are several types of integrity constraints that you can define. These include referential integrity, entity integrity, and domain integrity.
Referential integrity is a type of integrity constraint that requires that the values in a primary key or foreign key value in one table reference data in another table, called a parent table. This ensures that if a row in the parent table is deleted or updated, that the related data will also be affected.
The data in the referenced primary key or foreign key must be valid. If this is not the case, the integrity constraint will violate.
If a user inserts or updates a row that does not satisfy a referential integrity constraint, the statement will be rolled back. This is because the referenced key values must be valid and cannot be deleted or updated without violating the referential integrity constraint.
Typically, referential integrity constraints are implemented as a foreign key on the parent table and a primary key on the dependent table. The foreign key must be a column in the dependent table and must contain a valid reference to a value in the parent table.
In addition to a foreign key, referential integrity constraints may also be applied to a REF column. A REF column encapsulates a reference to a row object of a specified object type. These are usually created through a built-in data type or by a stored procedure in the database.
Non-null integrity is a type of integrity constraint for table columns that prohibits insertion or update of rows that do not have a value in that column. This is a rule that is included as part of the data entry process when a table is created or a row is inserted into a table.
Unlike the other types of integrity constraints, you can defer checking the validity of a non-null integrity constraint until the end of a transaction. If this is the case, the underlying SQL statement that caused the violation is rolled back and the entire transaction is rolled back.
Not null integrity
A not null integrity constraint requires that a column of a table contain no null values. This prevents the possibility of rows that conflict with an existing row’s data by requiring that the new row’s data match the values in the relevant column(s).
A NOT NULL integrity constraint is most often used with UNIQUE key constraints, which require that each value in a column or set of columns (key) be unique. A null in a UNIQUE key column or in all columns of a composite UNIQUE key always satisfies a NOT NULL integrity constraint, and no two rows in the table can have duplicate values in the corresponding column(s).
In addition to not allowing nulls in a UNIQUE key column, a NOT NULL integrity constraint prevents a table from being indexed by Oracle Database using a column that contains nulls. This is done to avoid index-only scans of the table and other types of operations that would require Oracle Database to index all rows in the table.
Unlike other types of integrity constraints, NOT NULL constraints can be deferrable, which means that you can specify that the constraint is not checked until a COMMIT statement has been issued. This means that a transaction can disable the not null integrity constraint until all of the changes to the table are completed.
As you can see from the above example, when a NOT NULL integrity constraint is enabled, the database checks the column after each statement executes to ensure that the inserted data complies with the rule. If the inserted data does not, then the database rolls back the statement and cancels any further execution of the statement.
The NOT NULL integrity constraint is also a self-referential constraint, which means that the value in the last name column is dependent on the value in the employees.last_name column in the EMP table. If a record is deleted in the employees table, then this record is automatically deleted from the last name table.
If you need to enforce the integrity of a table using logical expressions, then you should use CHECK constraints. These can be used when a NOT NULL or UNIQUE key cannot be specific enough to enforce the required integrity rules. CHECK constraints are most commonly used in conjunction with other types of integrity constraints to enforce complex rules.
Article integrity
Integrity is an important concept in many fields, including philosophy of action, science and technology, psychology, the human mind, the sciences, the arts, and politics. It is a quality that refers to what is right or wrong, good or bad, and the behavior of participants in governance in decision making and implementation.
Views of integrity vary, and they range from “being moral” to being a matter of “validity.” Some approaches, such as those that focus on values and norms, see integrity as an outcome or result of the behavior of a person, group, institution, or organization; other perspectives emphasize the behaviors themselves as the criteria for the assessment of integrity.
One common type of integrity constraint is the use of foreign keys to enforce referential consistency in a database. This is not a particularly hard task, and it can save you time by eliminating the need to manually ensure that all data in two tables refer to each other. However, it does not encapsulate the entire idea of referential integrity, which is much more complex.
Another way of implementing integrity constraints is through Boolean expressions. This is done by placing CHECK constraints on columns that have values to be inserted or updated in future rows.
These are evaluated with the corresponding value of the column about to be inserted or updated to determine whether the integrity rule is violated. If the row violates the integrity rule, it is considered to be null and will not be allowed.
Similarly, the use of check constraints is often useful when there are no other forms of integrity constraint that could be used to enforce the same condition. This is because a logical expression can be interpreted as both true and false, thus giving you an exact and precise answer to your integrity questions.
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