Aug 23

Difference between having and where clause Sql with example

Difference between where clause and Having clause with example

                         Where clause                Having clause
Where clause can be used with select,update,delete Having clause is used for only select query.
Where clause is applied on each and every row. Having clause is applied on group of rows. 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