SQL Constraints & Data Integrity



Constraints

  • NOT NULL Constraint: Ensures that a column cannot have NULL value.
  • DEFAULT Constraint: Provides a default value for a column when none is specified.
  • UNIQUE Constraint: Ensures that all values in a column are different.
  • PRIMARY Key: Uniquely identified each rows/records in a database table.
  • FOREIGN Key: Uniquely identified a rows/records in any another database table.
  • CHECK Constraint: The CHECK constraint ensures that all values in a column satisfy certain conditions.
  • INDEX: Use to create and retrieve data from the database very quickly

Data Integrity

  • Entity Integrity: There are no duplicate rows in a table.
  • Domain Integrity: Enforces valid entries for a given column by restricting the type, the format, or the range of values.
  • Referential Integrity: Rows cannot be deleted which are used by other records.
  • User-Defined Integrity: Enforces some specific business rules that do not fall into entity, domain, or
    referential integrity.

Комментарии

Популярные сообщения из этого блога

Beneficiaries and Disiribution database

Data Table Filters within Charts in Power BI