How to use Top Clause in SQL Server

SQL  Server TOP Clause
The TOP clause is used to specify the number of records to return in output from a Table.
The TOP clause can be very useful when we working on large tables with thousands of records. Returning a large number of records can impact on performance.

Syntax :
SELECT TOP number|percent column_name(s) FROM table_name

Example :
Let us suppose we have an EMPLOYEE Tables as follows :

Emp_ID	E_Name	Job	Dept_ID	Salary
1001	Ravi Teja Reddy	Analyst	1	20000
1002	Karun	Team Lead	2	35000
1003	Ravi Kumar Rao	Analyst	1	10000
1004	Tamatam	Team Lead	3	25000
1005	Sai Kumar Teja	Analyst	2	15000
1006	William	Manager	3	50000
1007	Vikram Teja Reddy	Analyst	2	18000
1008	Varun	Team Lead	1	33000
1009	Smith	Team Lead	3	50000

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Criteria-I : Now we want to select only the first two  records from the table above.
SELECT TOP 2 * From EMPLOYEE

Result :

Emp_ID	E_Name	Job	Dept_ID	Salary
1001	Ravi Teja Reddy	Analyst	1	20000
1002	Karun	Team Lead	2	35000

Now we want to select only the first two  records order by Salary.
SELECT TOP 2 * From EMPLOYEE Order By Salary

Result :

Emp_ID	E_Name	Job	Dept_ID	Salary
1003	Ravi Kumar Rao	Analyst	1	10000
1005	Sai Kumar Teja	Analyst	2	15000

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Criteria-II :
Now we want to select only 50% of the records in the table above.We use the following SELECT statement:
SELECT TOP 50 PERCENT *From EMPLOYEE

Result :

Emp_ID	E_Name	Job	Dept_ID	Salary
1001	Ravi Teja Reddy	Analyst	1	20000
1002	Karun	Team Lead	2	35000
1003	Ravi Kumar Rao	Analyst	1	10000
1004	Tamatam	Team Lead	3	25000
1005	Sai Kumar Teja	Analyst	2	15000

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