What are the Properties of Relational Tables?

Properties: All the values should be Atomic Each Column must have a unique name in the table All the Rows must be Unique All the values of a column are of same kind Ordering of columns is not necessary(doesn’t matter) Ordering of

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What are Global variables in SQL Server and how to create them?

In SQL Server, there is NO concept of Global variables. In the initial versions of SQL Server, the System defined functions which begin with ‘@@’ are referred as Global variables. But their actual behavior is not same as variables in SQL Server.

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What is Denormalization?

Denormalization is the process of optimizing the performance of a database by adding redundant data. It is the responsibility of database designer to denormalize up to some extent which should not impact the cost of the database. It plays vital role in

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What is the Difference between Temporary tables and Table Variables?

My suggestion is go for Table variables when we know that the structure of the table is not going to change in future. Otherwise go for Temporary tables. Happy Reading

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What is the difference between MINUS and LEFT JOIN in SQL Server?

This question seems to be very easy and you will start answering once you listen the question. But, be careful while answering very easy questions. Interviewer might test you by asking this kind of tricky questions. Don’t think that the questions were asked

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What are Magic tables?

Magic Tables: Magic tables are the virtual tables provided by SQL Server to store the recently inserted, deleted and updated values. Basically there are two types of magic tables in SQL Server namely ‘INSERTED‘ and ‘DELETED‘. These are much useful while working with

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What is a Dirty page?

Dirty page When we do any modification in the data, same will not be impacted in the physical table immediately. This follows a cycle to complete the action.  Modify the data in buffer cache pages – Called ‘Logical write’. Write the same

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What is the difference between ASCII() and CHAR() functions?

ASCII() vs CHAR(): ASCII() and CHAR() functions work with ASCII characters. But the functionality wise, both work quiet opposite. ASCII() function returns the ASCII code number for the given character as input. Where as, CHAR() function returns the ASCII character for the

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What is the difference between COALESCE() and ISNULL()?

Both functions are used to return the first not null value among all the input values passed. ISNULL(): It takes only two parameters. ISNULL() is T – SQL specific function. The return data type of ISNULL() is the datatype of the first

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How to change the file cached by Distributed Cache?

Distributed Cache in MapReduce can be updated by replacing the file with the new one and changing the pointer location to point to new location and restart the MapReduce job or by appending the values in Distributed cache and restarting the job.

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