SQL SERVER ( JOINS ) REAL TIME INTERVIEW QUESTIONS AND ANSWERS

1. What is a join and List different types of joins?
 Joins are used in queries to explain how different tables are related.Joins are also let you select data from a table depending upon data from another  table.
Types of JOINS :
--INNER JOIN
--OUTER JOIN
   LEFT OUTER JOIN,RIGHT OUTER JOIN,FULL OUTER JOIN
--CROSS JOIN
2. What are the differences between UNION and JOINS?
A join selects columns from two or tables.
A union selects rows.
3. What is the Referential Integrity?

4. What is a self-join? Explain it with an example?
5. How to join tables from different databases?
6. How to join tables from different servers?
7. What is a Cartesian product? What causes it?
8. T1 table having 7 rows and T2 table having 3 rows, How to find out missing rows from table T1?
9. What is the difference of a LEFT JOIN and an INNER JOIN statement?
10. Can i improve performance by using the ANSI-style joins instead of the old-style joins?