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SQL Server Interview Questions and Answers

When is the UPDATE_STATISTICS command used?
  • When the processing of large data is done, this command is used.
  • Whenever large number of deletions, modification or copy takes place into the tables, the indexes need to be updated to take care of these changes. UPDATE_STATISTICS performs this job.
What are DMVs?

Dynamic Management Views (DMVs), are functions that give you information on the state of the server. DMVs, for the most part, are used to monitor the health of a server. They really just give you a snapshot of what’s going on inside the server. They let you monitor the health of a server instance, troubleshoot major problems and tune the server to increase performance.

What is RDBMS?

Relational Data Base Management Systems (RDBMS) are database management systems that maintain data records and indices in tables. Relationships may be created and maintained across and among the data and tables. In a relational database, relationships between data items are expressed by means of tables. Interdependencies among these tables are expressed by data values rather than by pointers. This allows a high degree of data independence. An RDBMS has the capability to recombine the data items from different files, providing powerful tools for data usage.

What are tables and Fields?

A table is a set of data that are organized in a model with Columns and Rows. Columns can be categorized as vertical, and Rows are horizontal. A table has specified number of column called fields but can have any number of rows which is called record.

Table: Employee.

Field: Emp ID, Emp Name, Date of Birth.

Data: 201456, David, 11/15/1960.

Differentiate between a HAVING CLAUSE and a WHERE CLAUSE.


  • HAVING CLAUSE is used only with the SELECT statement.
  • It is generally used in a GROUP BY clause in a query.
  • If GROUP BY is not used, HAVING works like a WHERE clause.

WHERE Clause

  • It is applied to each row before they become a part of the GROUP BY function in a query.
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