How to find second highest or second maximum salary of an Employee is one
of the most frequently asked SQL interview question similar to finding duplicate records in table
and when to use truncate vs delete.
There are many ways to find second highest salary based upon which database you
are using as different database provides different feature which can be used to
find second maximum or Nth maximum salary of employee. Well this
question can also be generalized with other scenario like finding second
maximum age etc. In this SQL tutorial we will see different example of SELECT SQL query to find
second highest salary independent of databases or you may call in ANSI SQL and
other SQL queries which uses database specific feature to find second maximum
salary.
SQL query to find second maximum salary of Employee
In this section we will write SQL query to get second highest salary ofEmployee. Before writing query its good to be familiar with schema as well as
data in table. Here is the Employee table we will be using this SQL example:
mysql>
SELECT *
FROM Employee;
+--------+----------+---------+--------+
| emp_id |
emp_name | dept_id |
salary |
+--------+----------+---------+--------+
| 1
| James | 10
| 2000 |
| 2
| Jack | 10
| 4000 |
| 3
| Henry | 11
| 6000 |
| 4
| Tom
| 11
| 8000 |
+--------+----------+---------+--------+
4 rows IN
SET (0.00 sec)
If you look data, you will find that second maximum salary in this case
is 6000 and employee name is Henry. Now let’s see some SQL example to find out
this second maximum salary.
Second maximum salary using sub query and IN clause
Sub queries in SQL are great tool for this kind of scenario, here we first
select maximum salary and then another maximum excluding result of subquery. To
learn more about Subquery see correlate and non-correlate subquery in
SQL
mysql>
SELECT max(salary) FROM
Employee WHERE salary NOT IN
(SELECT
max(salary)
FROM Employee);
+-------------+
| max(salary) |
+-------------+
| 6000 |
+-------------+
1 row IN
SET (0.00 sec)
Here is another SQL query to find second highest salary using subquery
and < operator instead of IN clause:
mysql>
SELECT max(salary) FROM
Employee WHERE salary < (SELECT max(salary) FROM
Employee);
+-------------+
| max(salary) |
+-------------+
| 6000 |
+-------------+
1 row IN
SET (0.00 sec)
Both of above SQL example will work on all database including Oracle,
MySQL, Sybase and SQL Server as they are written using standard SQL keywords. But
sometime you can also use database specific features like TOP keyword of SQL
Server or Sybase database to find out second highest salary of Employee.
Second highest salary using TOP keyword of Sybase or SQL Server database
TOP keyword of Sybase and SQL Server database is used to select top
record or row of any result set, by carefully using TOP keyword you can find out
second maximum or Nth maximum salary as shown below.
SELECT TOP 1
salary FROM (
SELECT TOP 2
salary FROM employees ORDER BY
salary DESC)
AS emp ORDER
BY salary ASC
Here is what this SQL query is doing : First find out top 2 salary from Employee table and list them in descending order, Now
second highest salary of employee is at top so just take that value. Though you
need to keep in mind of using distinct keyword if there are more
than one employee with top salary, because in that case same salary will be
repeated and TOP 2 may list same salary twice.
Second maximum salary using LIMIT keyword of MYSQL database
LIMIT keyword of MySQL database is little bit similar with TOP keyword of
SQL Server database and allows to take only certain rows from result set. If
you look at below SQL example, its very much similar to SQL Server TOP keyword
example.
mysql>
SELECT salary FROM (SELECT salary FROM
Employee ORDER BY salary DESC
LIMIT 2) AS emp
ORDER BY
salary LIMIT 1;
+--------+
| salary |
+--------+
| 6000
|
+--------+
1 row IN
SET (0.00 sec)
That’s on How to find second highest salary of Employee using SQL query. This
is good question which really test your SQL knowledge, its not tough but
definitely tricky for beginners. As follow up question you can ask him to find
third maximum salary or Nth maximum salary as well.
Other SQL Interview Question answers you may like
Source:http://javarevisited.blogspot.com/2012/12/how-to-find-second-highest-or-maximum-salary-sql.html
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