Oracle Constraints Types Explained

In Oracle database, a variety of constraints can be used to ensure data integrity and consistency.

1. Primary Key Constraint: used to uniquely identify each row of data in a table and ensure that each row has a unique primary key value.
2. Foreign Key Constraint: Ensures that a foreign key in one table is related to a primary key or unique key value in another table, thus maintaining referential integrity between data.
3. Unique Constraint is used to ensure that the values in a column or group of columns in a table are unique, but unlike a primary key constraint, it allows for null values.
4. Check Constraint is used to define conditions for inserting, updating or deleting data in a table, ensuring that the data meets specific logical criteria.
5. Not Null Constraint: Ensures that a column in a table does not contain any null values, meaning that every row must have a value filled in for that column.
6. Default Constraint: this is used to define a default value that is automatically assigned to a column in a table when a new row is inserted without specifying a value.

These constraints can help database administrators and developers ensure the integrity of the data, enhance the stability and performance of the database.