MySQL Enterprise Server software is the most reliable, secure and up-to-date version of MySQL for cost-effectively delivering E-commerce, Online Transaction Processing (OLTP), and multi-terabyte Data Warehousing applications. It is a fully integrated transaction-safe, ACID compliant database with full commit, rollback, crash recovery and row level locking capabilities. MySQL delivers the ease of use, scalability, and performance that has made MySQL the world's most popular open source database.
MySql is a Relational database management system, provided from open source community. Currently fast growing and hight used RDBMS. MySql Developed by MySql AB.

Recovery Manager (or RMAN) is an Oracle provided utility for backing-up, restoring and recovering Oracle Databases. RMAN ships with the database server and doesn’t require a separate installation. The RMAN executable is located in your ORACLE_HOME/bin directory.

Foreign keys definitions are subject to the following conditions:
Both tables must be InnoDB tables and they must not be TEMPORARY tables.
In the referencing table, there must be an index where the foreign key columns are listed as the first columns in the same order. Such an index is created on the referencing table automatically if it does not exist.
In the referenced table, there must be an index where the referenced columns are listed as the first columns in the same order.
Index prefixes on foreign key columns are not supported. One consequence of this is that BLOB and TEXT columns cannot be included in a foreign key, because indexes on those columns must always include a prefix length.
If the CONSTRAINT symbol clause is given, the symbol value must be unique in the database. If the clause is not given, InnoDB creates the name automatically.

Select date_format(curdate(),'%M') ;

select to_char(sysdate,'Month') from dual

Each row has two additional columns associated with it - creation time and deletion time, but instead of storing timestamps, MySQL stores version numbers
Multiversion concurrency control (abbreviated MCC or MVCC), in the database field of computer science, is a concurrency control method commonly used by database management systems to provide concurrent access to the database. MVCC provides each user connected to the database with a "snapshot" of the database for that person to work with. Any changes made will not be seen by other users of the database until the transaction has been committed.

Set of statements to perform a particular task.It compute a value and returns it.
if u call 1000 times a function,it has the same effect.It cannot be executed individually.
When u call a function,u must assign a value to the variable.
Note:Returns a single value.

There are five types of constraints:-

1. PRIMARY constraint
2.FOREIGN constraint
3.UNIQUE constraint
4.CHECK constraint
5.DEFAULT constraint