Explain various types of constraints in Oracle.Oracle "Check" Constraint:
It validates incoming columns at row insert time.
Not Null Constraint:
It is used to specify that a column may never contain a NULL value.
Primary Key Constraint:
It is used to identify the primary key for a table. This operation requires that the primary columns are unique, and it creates a unique index on the target primary key.
This is the foreign key constraint and is only applied during INSERT and DELETE.
It is used to ensure that all column values within a table never contain a duplicate entry.