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SQL interview questions

SQL interview questions.

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1.

Define a temp table

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2.

What is a view?

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3.

What is PRIMARY KEY?

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What is blocking?

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What is Normalization?

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6.

What is the difference between WHERE clause and HAVING clause?

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7.

What is DEFAULT?

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8.

What is FOREIGN KEY?

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9.

What’s the difference between a local temp table and a global temp table?

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10.

How can a column with a default value be added to an existing table?

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11.

Is table size reduced, when you delete data from the table?

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12.

Define ACID Properties

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13.

Discuss INNER JOIN ON vs WHERE clause

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14.

What is the difference between “INNER JOIN” and “OUTER JOIN”?

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15.

What is the difference between JOIN and UNION?

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16.

What is the difference between UNION and UNION ALL?

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17.

What are the advantages of using Stored Procedures?

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18.

How do I perform an IF…THEN in an SQL SELECT?

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19.

What is the difference between inner and outer join?

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20.

Describe the difference between truncate and delete

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21.

What is Denormalization?

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22.

What are the difference between clustered and a non-clustered index?

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23.

How a database index can help performance?

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24.

What is a cursor how does it work?

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25.

What are row constructors?

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26.

Explain Function vs. Stored Procedure in SQL Server

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27.

What is collation?

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28.

Finding duplicate values in a SQL table

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29.

How to select first 5 records from a table?

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30.

How does a hash table index work?

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31.

How do I UPDATE from a SELECT in SQL Server?

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32.

What is a filegroup?

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33.

What is the cost of having a database index?

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34.

How does truncate and delete operation effect Identity?

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35.

What are DMV's and DMF's?

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36.

How does B-trees index work?

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37.

How deadlock is resolved?

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38.

What are statistics?

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39.

What is a linked server?

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40.

Explain the difference between exclusive lock and update lock

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41.

What is the difference among UNION, MINUS and INTERSECT?

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42.

How can we transpose a table using SQL (changing rows to column or vice-versa) ?

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43.

What's the difference between a primary key and a unique key?

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44.

Name types of Triggers

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45.

Explain a usage difference between user defined functions and stored procedures

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46.

What is Optimistic Locking and Pessimistic locking?

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47.

Select first row in each GROUP BY group (greatest-n-per-group problem)?

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48.

How does database indexing work?

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49.

What are some other types of indexes?

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50.

Name some disadvantages of a hash index

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51.

How does primary key constraint and unique key constraint effect null?

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52.

How can I do an UPDATE statement with JOIN in SQL?

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53.

How to generate row number in SQL Without ROWNUM

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54.

What would happen without an index?

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55.

Delete duplicate values in a SQL table

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56.

Insert results of a stored procedure into a temporary table

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