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SQL Query Interview Questions and Answers with Examples

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30. Get employee details from employee table whose joining year is “2013”
SQL Queries in Oracle, Select * from EMPLOYEE where to_char(joining_date,'YYYY')='2013'

SQL Queries in SQL Server, Select * from EMPLOYEE where SUBSTRING(convert(varchar,joining_date,103),7,4)='2013'

SQL Queries in MySQL, Select * from EMPLOYEE where year(joining_date)='2013'

31. Get employee details from employee table whose joining month is “January”
SQL Queries in Oracle, Select * from EMPLOYEE where to_char(joining_date,'MM')='01' or Select * from EMPLOYEE where to_char(joining_date,'Mon')='Jan'

SQL Queries in SQL Server, Select * from EMPLOYEE where SUBSTRING(convert(varchar,joining_date,100),1,3)='Jan'

SQL Queries in MySQL, Select * from EMPLOYEE where month(joining_date)='01'
32. Get employee details from employee table who joined before January 1st 2013
SQL Queries in Oracle, Select * from EMPLOYEE where JOINING_DATE <to_date('01/01/2013','dd/mm/yyyy')

SQL Queries in SQL Server (Format - “MM/DD/YYYY”), Select * from EMPLOYEE where joining_date <'01/01/2013'

SQL Queries in MySQL (Format - “YYYY-DD-MM”), Select * from EMPLOYEE where joining_date <'2013-01-01'

33. Get employee details from employee table who joined after January 31st
SQL Queries in Oracle, Select * from EMPLOYEE where JOINING_DATE >to_date('31/01/2013','dd/mm/yyyy')

SQL Queries in SQL Server and MySQL (Format - “MM/DD/YYYY”), Select * from EMPLOYEE where joining_date >'01/31/2013'

SQL Queries in MySQL (Format - “YYYY-DD-MM”), Select * from EMPLOYEE where joining_date >'2013-01-31'


35. Get Joining Date and Time from employee table
SQL Queries in Oracle, select to_char(JOINING_DATE,'dd/mm/yyyy hh:mi:ss') from EMPLOYEE

SQL Queries in SQL Server, Select convert(varchar(19),joining_date,121) from EMPLOYEE

SQL Queries in MySQL, Select CONVERT(DATE_FORMAT(joining_date,'%Y-%m-%d-%H:%i:00'),DATETIME) from EMPLOYEE

36. Get Joining Date,Time including milliseconds from employee table
SQL Queries in Oracle, select to_char(JOINING_DATE,'dd/mm/yyyy HH:mi:ss.ff') from EMPLOYEE . Column Data Type should be “TimeStamp”

SQL Queries in SQL Server, select convert(varchar,joining_date,121) from EMPLOYEE

SQL Queries in MySQL, Select MICROSECOND(joining_date) from EMPLOYEE

37. Get difference between JOINING_DATE and INCENTIVE_DATE from employee and incentives table
Select FIRST_NAME,INCENTIVE_DATE - JOINING_DATE from employee a inner join incentives B on A.EMPLOYEE_ID=B.EMPLOYEE_REF_ID

38. Get database date
SQL Queries in Oracle, select sysdate from dual

SQL Queries in SQL Server, select getdate()

SQL Query in MySQL, select now()
39. Get names of employees from employee table who has '%' in Last_Name. Tip : Escape character for special characters in a query.
SQL Queries in Oracle, Select FIRST_NAME from employee where Last_Name like '%?%%'

SQL Queries in SQL Server, Select FIRST_NAME from employee where Last_Name like '%[%]%'

SQL Queries in MySQL, Select FIRST_NAME from employee where Last_Name like '%\%%'

40. Get Last Name from employee table after replacing special character with white space
SQL Queries in Oracle, Select translate(LAST_NAME,'%',' ') from employee

SQL Queries in SQL Server and MySQL, Select REPLACE(LAST_NAME,'%',' ') from employee

"SQL Group By Query" Interview Questions and Answers

41. Get department,total salary with respect to a department from employee table.
Select DEPARTMENT,sum(SALARY) Total_Salary from employee group by department

42. Get department,total salary with respect to a department from employee table order by total salary descending
Select DEPARTMENT,sum(SALARY) Total_Salary from employee group by DEPARTMENT order by Total_Salary descending

SQL Queries Interview Questions and Answers on "SQL Mathematical Operations using Group By"

43. Get department,no of employees in a department,total salary with respect to a department from employee table order by total salary descending
Select DEPARTMENT,count(FIRST_NAME),sum(SALARY) Total_Salary from employee group by DEPARTMENT order by Total_Salary descending

44. Get department wise average salary from employee table order by salary ascending
select DEPARTMENT,avg(SALARY) AvgSalary from employee group by DEPARTMENT order by AvgSalary asc

45. Get department wise maximum salary from employee table order by salary ascending
select DEPARTMENT,max(SALARY) MaxSalary from employee group by DEPARTMENT order by MaxSalary asc

46. Get department wise minimum salary from employee table order by salary ascending
select DEPARTMENT,min(SALARY) MinSalary from employee group by DEPARTMENT order by MinSalary asc

47. Select no of employees joined with respect to year and month from employee table
SQL Queries in Oracle, select to_char (JOINING_DATE,'YYYY') Join_Year,to_char (JOINING_DATE,'MM') Join_Month,count(*) Total_Emp from employee group by to_char (JOINING_DATE,'YYYY'),to_char(JOINING_DATE,'MM')

SQL Queries in SQL Server, select datepart (YYYY,JOINING_DATE) Join_Year,datepart (MM,JOINING_DATE) Join_Month,count(*) Total_Emp from employee group by datepart(YYYY,JOINING_DATE), datepart(MM,JOINING_DATE)

SQL Queries in MySQL, select year (JOINING_DATE) Join_Year,month (JOINING_DATE) Join_Month,count(*) Total_Emp from employee group by year(JOINING_DATE), month(JOINING_DATE)

48. Select department,total salary with respect to a department from employee table where total salary greater than 800000 order by Total_Salary descending
Select DEPARTMENT,sum(SALARY) Total_Salary from employee group by DEPARTMENT having sum(SALARY) >800000 order by Total_Salary desc

49. Select employee details from employee table if data exists in incentive table ?


select * from EMPLOYEE where exists (select * from INCENTIVES)
Explanation : Here "exists" statement helps us to do the job of If statement. Main query will get executed if the sub query returns at least one row. So we can consider the sub query as "If condition" and the main query as "code block" inside the If condition. We can use any SQL commands (Joins, Group By , having etc) in sub query. This command will be useful in queries which need to detect an event and do some activity.
50. How to fetch data that are common in two query results ?
select * from EMPLOYEE where EMPLOYEE_ID INTERSECT select * from EMPLOYEE where EMPLOYEE_ID < 4
Explanation : Here "INTERSECT" command is used to fetch data that are common in 2 queries. In this example, we had taken EMPLOYEE table in both the queries.We can apply INTERSECT command on different tables. The result of the above query will return employee details of "ROY" because, employee id of ROY is 3, and both query results have the information about ROY.
51. Get Employee ID's of those employees who didn't receive incentives without using sub query ?
select EMPLOYEE_ID from EMPLOYEE
MINUS
select EMPLOYEE_REF_ID from INCENTIVES
Explanation : To filter out certain information we use MINUS command. What MINUS Command odes is that, it returns all the results from the first query, that are not part of the second query. In our example, first three employees received the incentives. So query will return employee id's 4 to 8.
52. Select 20 % of salary from John , 10% of Salary for Roy and for other 15 % of salary from employee table
SELECT FIRST_NAME, CASE FIRST_NAME WHEN 'John' THEN SALARY * .2 WHEN 'Roy' THEN SALARY * .10 ELSE SALARY * .15 END "Deduced_Amount" FROM EMPLOYEE
Explanation : Here, we are using "SQL CASE" statement to achieve the desired results. After case statement, we had to specify the column on which filtering is applied. In our case it is "FIRST_NAME". And in then condition, specify the name of filter like John, Roy etc. To handle conditions outside our filter, use else block where every one other than John and Roy enters.
53. Select Banking as 'Bank Dept', Insurance as 'Insurance Dept' and Services as 'Services Dept' from employee table
SQL Queries in Oracle, SELECT distinct DECODE (DEPARTMENT, 'Banking', 'Bank Dept', 'Insurance', 'Insurance Dept', 'Services', 'Services Dept') FROM EMPLOYEE
SQL Queries in SQL Server and MySQL, SELECT case DEPARTMENT when 'Banking' then 'Bank Dept' when 'Insurance' then 'Insurance Dept' when 'Services' then 'Services Dept' end FROM EMPLOYEE
Explanation : Here "DECODE" keyword is used to specify the alias name. In oracle we had specify, Column Name followed by Actual Name and Alias Name as arguments. In SQL Server and MySQL, we can use the earlier switch case statements for alias names.
54. Delete employee data from employee table who got incentives in incentive table
delete from EMPLOYEE where EMPLOYEE_ID in (select EMPLOYEE_REF_ID from INCENTIVES)
Explanation : Trick about this question is that we can't delete data from a table based on some condition in another table by joining them. Here to delete multiple entries from EMPLOYEE table, we need to use Subquery. Entries will get deleted based on the result of Subquery.
55. Insert into employee table Last Name with " ' " (Single Quote - Special Character)
Tip - Use another single quote before special character
Insert into employee (LAST_NAME) values ('Test''')
56. Select Last Name from employee table which contain only numbers
Select * from EMPLOYEE where lower(LAST_NAME)=upper(LAST_NAME)
Explanation : In order to achieve the desired result, we use "ASCII" property of the database. If we get results for a column using Lower and Upper commands, ASCII of both results will be same for numbers. If there is any alphabets in the column, results will differ.
57. Write a query to rank employees based on their incentives for a month
select FIRST_NAME,INCENTIVE_AMOUNT,DENSE_RANK() OVER (PARTITION BY INCENTIVE_DATE ORDER BY INCENTIVE_AMOUNT DESC) AS Rank from EMPLOYEE a, INCENTIVES b where a.EMPLOYEE_ID=b.EMPLOYEE_REF_ID
Explanation : In order to rank employees based on their rank for a month, "DENSE_RANK" keyword is used. Here partition by keyword helps us to sort the column with which filtering is done. Rank is provided to the column specified in the order by statement. The above query ranks employees with respect to their incentives for a given month.
58. Update incentive table where employee name is 'John'
update INCENTIVES set INCENTIVE_AMOUNT='9000' where EMPLOYEE_REF_ID=(select EMPLOYEE_ID from EMPLOYEE where FIRST_NAME='John' )
Explanation : We need to join Employee and Incentive Table for updating the incentive amount. But for update statement joining query wont work. We need to use sub query to update the data in the incentive table. SQL Query is as shown below.

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