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Database - Interview Questions and Answers for 'Accenture' - 7 question(s) found - Order By Newest | ||||
Frequently asked in Cognizant ( Based on 2 feedback ) | ||||
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Ans. Inner join is the intersection of two tables on the condition defined by the where clause i.e will get records from both tables matched by a column. Outer join is the union of two tables i.e will get all records from both tables and will put null in the columns where related records are not present. Left Outer join is the left union of two tables i.e all records from the table on the left and values from the right table for related records else null for the columns from right table. Right Outer join is the right union of two tables i.e all records from the table on the right and values from the left table for related records else null for the columns from left table. | ||||
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Like Discuss Correct / Improve  sql  inner join  outer join  right join  left join Asked in 24 Companies basic   frequent | ||||
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Ans. When a Table Join itself , it's a Self Join. For example - we like to know the pair of department names where first dept has lesser employees than the later. Select D1.name , D2.name from Dept D1, Dept D2 where D1.employee_count < D2.employee_count | ||||
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Like Discuss Correct / Improve  sql  joins  self join  self-join  Pair of employee names with first having lesser salary than later  Pair of department names where first dept has lesser employees than the later Asked in 26 Companies basic   frequent | ||||
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Ans. https://en.wikipedia.org/wiki/Database_normalization | ||||
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Like Discuss Correct / Improve  normalization  database Asked in 35 Companies intermediate   frequent | ||||
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Ans. JDBC is a standard Java Api for Database communication whereas Hibernate is an ORM framework that uses JDBC to connect with Database. Hibernate is another layer of object table mapping over JDBC that provide a database independent, object oriented and an efficient way of database communication. | ||||
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Like Discuss Correct / Improve  JDBC  Hibernate  JDBC vs Hibernate Asked in 3 Companies | ||||
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Ans. DELETE FROM TABLE WHERE ROW_NUM NOT IN ( SELECT MAX(ROW_ID) FROM TABLE GROUP BY DUPLICATE_FIELD ) | ||||
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Like Discuss Correct / Improve   Asked in 3 Companies | ||||
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Ans. DELETE FROM TABLE WHERE ROW_NUM NOT IN ( SELECT MAX(ROW_ID) FROM TABLE GROUP BY DUPLICATE_FIELD ) or DELETE FROM TABLE a WHERE ROW_ID >(SELECT MIN(ROW_ID FROM TABLE b WHERE a.DUPLICATE_FIELD=b.DUPLICATE_FIELD); | ||||
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Like Discuss Correct / Improve   Asked in 3 Companies | ||||
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Ans. We can have 2 entities i.e EMPLOYEE and ADDRESS and can have a relationship Table , EMPLOYEE_ADDRESS having one to may relationship between the two. | ||||
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Like Discuss Correct / Improve  database schema   design Asked in 2 Companies | ||||