Defining table _ creates links between tables that identify a correspondence of fields from one table to another.
A. connections
B. codependencies
C. interlocutions
D. relationships
The Correct Answer and Explanation is:
The correct answer is D. relationships.
In database design, defining relationships between tables is crucial for establishing how data in one table corresponds to data in another. Relationships are used to link tables in a relational database, ensuring data integrity and enabling more efficient querying. Here’s a detailed explanation of the concept:
Explanation:
Relational databases organize data into tables (or “relations”) that are related to each other through shared fields, known as keys. There are several types of relationships in relational databases:
- One-to-One (1:1): This relationship occurs when a record in one table is associated with only one record in another table. For example, a table containing employee details might be linked to a table with employee IDs, where each employee ID corresponds to exactly one employee.
- One-to-Many (1:M): In this type of relationship, a single record in one table can relate to multiple records in another table. For example, one customer might have multiple orders in an orders table, but each order is linked to only one customer.
- Many-to-Many (M:N): This relationship happens when multiple records in one table are associated with multiple records in another table. For instance, students and courses might have a many-to-many relationship, where each student can enroll in multiple courses, and each course can have multiple students. This often requires a third “junction” table to manage the relationship.
To establish these relationships, a field from one table is typically linked to a corresponding field in another table. These fields are known as foreign keys (in the child table) and primary keys (in the parent table). The foreign key refers to the primary key in another table, creating a connection between the tables and ensuring referential integrity. This allows for easy retrieval of related data using SQL queries with JOIN operations.
In summary, relationships are the foundational concept that connects tables, ensures data consistency, and supports efficient database management and querying. Without these relationships, databases would lack structure, making it difficult to query and retrieve meaningful insights from related data.