MySQL

Basic Fundamentals

Date Functions

CURDATE() – return current date
CURRENT DATE() – return current date
CURRENT TIME() – return current date

List of Database

SHOW DATABASES;

Current Database

SELECT DATABASE();

MySQL has six distinct table types.

MYISAM
MERGE
ISAM
HEAP
INNODB
BDB

Default type of MySQL is MYISAM.

Difference between MYISAM and InnoDB.

The main Difference is InnoDB support transactions. you can do commit and rollback in InnoDB where as in MYISAM doesn’t support transaction once issue command can’t rollback.

MYISAM does table locking where as InnoDB do row locking. if your App does lots of data modification then InnoDB is best and Faster.

Types of PL/SQL trigger

Row level trigger
Statement level trigger

1) Row level Trigger : An event is triggered for each row updated, inserted and deleted.

2) Statement level Trigger : An event is triggered for each SQL statement executed.

what is max length for dbname, tablename, and fieldname?

ans: 64

For value 0/1 which datatype is used ?

ans: tinyINT

Difference between two date ?

select DATEDIFF(NOW(), ’2006-07-01′);