Constraints, Rules, Defaults, and Triggers
Table columns have properties other than data type and size. These other properties are an important part in ensuring the integrity of data in a database:
- Data integrity refers to each occurrence of a column having a correct data value.
The data values must be of the right data type and in the correct domain.
- Referential integrity indicates that the relationships between tables have been properly maintained.
Data in one table should only point to existing rows in another table; it should not point to rows that do not exist.
Objects used to maintain both types of integrity include: