Data Intigrity in SQL Server

Data Intigrity:-

• Enforce the business rules into the database . This is called as Data Intigrity.'
• Enforcing  Data Intigrity ensures the quality of data in the Data base.

Three Types of Data Intigrities are available.

• Domain Intigrity
• Entity Intigrity
• Referential Intigrity

Domain Intigrity:-

Domain ( or Column) intigrity specifies a set of of data values that are valid for a column and determines whether to allow null values.Domain integrity is ofter enforced by using validity checking and can be enforced by restricting the data type, format, or range of possible values allowed in a column.

Entity Intigrity:-

Entity (or Table) intigrity requires that all rows in a table have a unique identifier, known as the primary key values. Whether the primary key values can be changed, or whether the whole row can be deleted, depends on the level of intigrity required between the primary key and any other tables.

Referential Integrity:-

Referential Intigrity ensurses that the relationships among the primary keys(In the referential table) and foreign keys are always maintained.

A row in a referenced tablecan not be deleted, nor can primary key be changed. If a foreign key refers to the row, unless the cascade action is permitted.

We can define refential integrity relationships whithin the same table or between seperate table.