Oracle Database Constraints Quiz

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Questions and Answers

Match the following RDBMS integrity constraints with their descriptions:

Entity Integrity Constraints = Restrict the values in a row of an individual table Referential Integrity Constraints = Specifies that a row of one table that refers to another row must refer to an existing row in that table Domain Integrity Constraints = Includes Not null and Check constraints Key Constraints = Subcategory of Entity Integrity Constraints

Match the following characteristics of NULL value with their descriptions:

A NULL value distinct from zero or other numeric value for numerical data = Characteristic of NULL value A NULL value indicates ‘not applicable’, ‘missing’, or ‘not known’ = Characteristic of NULL value General-purpose programming = Python Client-side scripting for web applications = JavaScript

Match the following subcategories of Entity Integrity Constraints with their descriptions:

Domain Integrity Constraints = Subcategory of Entity Integrity Constraints Key Constraints = Subcategory of Entity Integrity Constraints Restrict the values in a row of an individual table = Entity Integrity Constraints Specifies that a row of one table that refers to another row must refer to an existing row in that table = Referential Integrity Constraints

Match the following general characteristics of Constraints provided by Oracle with their descriptions:

A rule that restricts the values that may be present in the database = Constraint Constraints provided by Oracle follows the general Constraints provided by relational model = Oracle-based Constraints Database queries = SQL Styling web pages = CSS Signup and view all the answers

Match the following descriptions of NOT NULL Constraints with their characteristics:

There may be Records in table that do not contain any value for some fields = NOT NULL Constraints Null values are stored in such fields, representing an empty field = NOT NULL Constraints Subcategory of Entity Integrity Constraints = Key Constraints Specifies that a row of one table that refers to another row must refer to an existing row in that table = Referential Integrity Constraints Signup and view all the answers

Explain the two broad categories into which database integrity constraints can be classified.

The two broad categories into which database integrity constraints can be classified are Entity Integrity Constraints and Referential Integrity Constraints. Signup and view all the answers

What are Entity Integrity Constraints and how are they further classified?

Entity Integrity Constraints are constraints that restrict the values in a row of an individual table. They are further classified into Domain Integrity Constraints and Key Constraints. Signup and view all the answers

What is the purpose of Referential Integrity Constraints?

Referential Integrity Constraints specify that a row of one table that refers to another row must refer to an existing row in that table. Signup and view all the answers

Explain the NOT NULL Constraints in Oracle and their characteristics.

The NOT NULL Constraints ensure that there are no records in a table that do not contain any value for certain fields. In Oracle, Null values are stored in such fields. A NULL value represents 'not applicable', 'missing', or 'not known', and is distinct from zero or other numeric values for numerical data. Signup and view all the answers

How are NULL values stored in Oracle and what do they represent?

In Oracle, Null values are stored in fields that do not contain any value. A NULL value represents 'not applicable', 'missing', or 'not known', and is distinct from zero or other numeric values for numerical data. Signup and view all the answers

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Study Notes

RDBMS Integrity Constraints

Integrity constraints are rules to ensure data accuracy and consistency within a relational database management system (RDBMS).
Common types include entity integrity, referential integrity, and domain integrity.

Characteristics of NULL Values

NULL represents the absence of a value, not zero or an empty string.
Queries with NULL values require special handling; operators like "=", "<>", or "IS NULL" behave differently.
NULL can lead to complications in aggregate functions, as they are usually ignored.

Entity Integrity Constraints

Ensure that each entity (row) in a table is unique and identifiable.
Subcategories include:
- Primary Key Constraints: Enforce uniqueness for a column or set of columns.
- Unique Constraints: Guarantee that all values in a column are different but allow NULLs.

Oracle Constraints Characteristics

Oracle databases provide comprehensive constraint definitions for data integrity.
They include NOT NULL, UNIQUE, PRIMARY KEY, FOREIGN KEY, and CHECK constraints.
Constraints can affect performance; excessive use may slow down operations due to overhead.

NOT NULL Constraints

Prevent the insertion of NULL values in specified columns, ensuring data integrity.
Commonly used for columns that require mandatory data entry.
Helps enforce business rules by maintaining essential information.

Categories of Database Integrity Constraints

Integrity constraints can be classified into two broad categories:
- Entity Integrity Constraints: Ensure uniqueness and validity of data entries.
- Referential Integrity Constraints: Maintain consistent references between related tables.

Purpose of Referential Integrity Constraints

Protect relationships between tables by ensuring that foreign keys correspond to valid primary keys.
Prevent orphan records, thus maintaining relational data integrity.

NOT NULL Constraints in Oracle

NOT NULL constraints prevent columns from having a NULL value, mandating a valid entry.
Ensures crucial information is always available for data processing and querying.

Storage of NULL Values in Oracle

NULL values are stored by having a specific indicator flag rather than an actual value.
Represent unknown or inapplicable information for a specific column.