Similarity: Both WHERE and HAVING Clause filters out records based on one or more conditions.

Difference: WHERE Clause can only be applied to a static non-aggregated column whereas HAVING is needed for aggregated columns.

SQL JOIN allows access to records of other table based on the given conditions between two tables.

Ex: If we are provided with the department ID of each employee, then we can use the department ID of the employee table to merge with the department ID of the department table to access department names.

UNION operation allows addition of 2 similar data sets to create a resulting set that contains all the data from the source data sets.

Ex: If we are provided with 2 employee tables of the same structure, we can UNION them to create a singular result that will contain all employee from both the table.

An SQL statement is a string of characters that conforms to the syntax and format specified in the international standard.

A query is a statement that returns a record-set.

SELECT SERVERPROPERTY ('productversion'), SERVERPROPERTY ('productlevel') and SERVERPROPERTY ('edition').

This command is used when a large processing of data has occurred. If any large amount of deletions, any modifications, or Bulk Copy into the tables has occurred, it has to update the indexes to take these changes into account. UPDATE_STATISTICS updates the indexes on these tables accordingly.

- A clustered index is a special type of index that reorders the way records in the table are physically stored. Therefore table can have only one clustered index.

- A non clustered index is a special type of index in which the logical order of the index does not match the physical stored order of the rows on disk. The leaf node of a non clustered index does not consist of the data pages. Instead, the leaf nodes contain index rows.

Inbound customer service agents handle incoming calls from customers for:

- Requests for help

- Inquiries or requests for information

- Placing orders, in product purchases

- Applications for services

- Filing complaints

Outbound customer service agents make calls to random potential customers to sell a service or product. These agents can also be called as telemarketing executives.

KPO stands for Knowledge Process Outsourcing. It is a subset of call centers. The ways in which a KPO differs from a call center are :

1. In KPO knowledge and information related work is carried out.

2. Staff requirement is for highly skilled people.

3. Is mainly related to support and not sales.

4. Carries out works mainly for research and analysis process besides support.