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6.	Define Primary Key?
	The primary key is the columns used to uniquely identify each row of a table. A table can have only one primary key. No primary key value can appear in more than one row in the table.
	Discuss Baburao Adkane, said Mar 16, 2014 A primary key is a key uniquely identifies a field/row of the table. A primary key does not contain a NULL value. A table can have only one primary key. A primary key is applicable to one or more fields of the table. A primary key is applied to more than one field then it is called the Candidate Key. Your Name Your Email-ID Your Answer

7.	Define Unique Key?
	Unique key is a one or more column that must be unique for each row of the table. It is similar to primary key. Primary key column will not accept a null. Whereas the unique key column will accept a null values.
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8.	Compare and contrast TRUNCATE and DELETE for a table?
	Both the truncate and delete command have the desired outcome of getting rid of all the rows in a table. The difference between the two is that the truncate command is a DDL operation and just moves the high water mark and produces a now rollback. The delete command, on the other hand, is a DML operation, which will produce a rollback and thus take longer to complete.
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9.	What is cursors?
	Cursor is a database object used by applications to manipulate data in a set on a row-by-row basis, instead of the typical SQL commands that operate on all the rows in the set at one time.
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10.	Define Foreign Key?
	A foreign Key is a combination of columns with value is based on the primary key values from another table. A foreign key constraint also known as Referential Integrity Constraint.
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