RELATIONAL MODEL II

CONTENT

• Integrity Constraints over Relations
• Single-Field Constraints
• Multiple-Field Constraints

Integrity Constraints over Relations

In relational databases, the concept of integrity constraints plays a crucial role in ensuring the quality and consistency of data. These constraints establish logical conditions that fields, or combinations of fields, must adhere to when data is inserted. Their primary purpose is to govern the type of data that can be stored within a table or specific fields. Let’s delve deeper into this essential aspect of database management.

Unique Constraints:

One fundamental form of integrity constraint is the UNIQUE constraint. This constraint serves to restrict a field from accepting values that would lead to the duplication of existing values within the same field. In essence, it enforces the uniqueness of values in a particular column.

Relationship Constraints:

Another crucial type of constraint in the realm of database management is the relationship constraint. Unlike other constraints, relationship constraints do not require a specific keyword to indicate their presence; instead, they rely on the values of a field or a combination of fields in another table to determine whether a value can be inserted into the constrained field or combination of fields.