Jun 30

Mysql interview questions and answers for freshers-part-1

1) Explain what are identifiers and rules for defining identifiers in mysql?

Identifiers are names of columns,tables,indexes,views,Stored Procedures,Triggers etc.

Identifiers can start with any character including digit, but it should not consists of completely digits.

Identifiers can consists of letters,digits,dollar,underscore.

An Identifiers names can have a maximum length of 64 characters.

An alias name can have a maximum characters of up to 255 characters. Continue reading

Jun 24

Object class interview questions and answers in java-part 49

241)      Explain importance of Object class in java?

java.lang.Object class represents java object. Object class is the super class for all predefined and user defined classes in java.Each and every class in java extends Object class. Methods defined in Object class are important because they appear in every instance of class. Continue reading

Jun 04

Oracle sql interview questions and answers part-1

1)      Explain primary key?

Primary key : Primary key is used to uniquely identify a row in table.

Each table can have only one primary key.

We cannot insert nulls for primary key values.

We cannot insert duplicate values in primary key column.

Example : For example if we take Students table students table contains student id, which is used to uniquely identify a record in table. Continue reading