When an instance of an ORACLE database is started, its control file is used to identify the database and redo log files that must be opened for database operation to proceed. It is also used in database recovery
Control files is a binary file. Before database is opened it determines whether database is in valid state or not. If yes then database is opened.
Yes a View based on another View in Oracle
The Primary function of the redo log is to record all changes made to data
NOT NULL Constraint - Disallows Nulls in a table's column
UNIQUE Constraint - Disallows duplicate values in a column or set of columns
PRIMARY KEY Constraint - Disallows duplicate values and Nulls in a column or set of columns.
FOREIGN KEY Constrain - Require each value in a column or set of columns match a value in a related table's UNIQUE or PRIMARY KEY.
CHECK Constraint - Disallows values that do not satisfy the logical expression of the constraint.
The data dictionary of an ORACLE database is a set of tables and views that are used as a read-only reference about the database.
It stores information about both the logical and physical structure of the database, the valid users of an ORACLE database, integrity constraints defined for tables in the database and space allocated for a schema object and how much of it is being used.