Oracle SQL Queries Most Frequently Asked In Huawei Written Test Interview
How to retrieve 2nd highest sal in each departement from emp and dept tables using GROUP BY?
SELECT e.DeptNo, MAX(e.Sal),d.DeptName Salary
FROM Emp e left outer join dept d ON e.DeptNo=d.DeptNo
WHERE e.Sal <
(SELECT MAX(Sal)
FROM Emp
WHERE DeptNo = e.DeptNo)
GROUP BY e.DeptNo,d.DeptName
Find the 3rd MAX and MIN salary in the emp table?
select distinct sal from emp e1 where 3 = (select count(distinct sal) from emp e2 where e1.sal <= e2.sal);
select distinct sal from emp e1 where 3 = (select count(distinct sal) from emp e2where e1.sal >= e2.sal);
If there are two tables emp1 and emp2, and both have common record. How can I fetch all the records but common records only once?
(Select * from emp) Union (Select * from emp1)
How to fetch only common records from two tables emp and emp1?
(Select * from emp) Intersect (Select * from emp1)
How can I retrive all records of emp1 those should not present in emp2?
(Select * from emp) Minus (Select * from emp1)
Get the first day of the month?
Quickly returns the first day of current month. Instead of current month you want to find first day of month where a date falls, replace SYSDATE with any date column/value.
SELECT TRUNC (SYSDATE, 'MONTH') "First day of current month"
FROM DUAL;
Get the last day of the month?
This query is similar to above but returns last day of current month. One thing worth noting is that it automatically takes care of leap year. So if you have 29 days in Feb, it will return 29/2. Also similar to above query replace SYSDATE with any other date column/value to find last day of that particular month.
SELECT TRUNC (LAST_DAY (SYSDATE)) "Last day of current month"
FROM DUAL;
Get the first day of the Year
First day of year is always 1-Jan. This query can be use in stored procedure where you quickly want first day of year for some calculation.
SELECT TRUNC (SYSDATE, 'YEAR') "Year First Day" FROM DUAL;
Get the last day of the year
Similar to above query. Instead of first day this query returns last day of current year.
SELECT ADD_MONTHS (TRUNC (SYSDATE, 'YEAR'), 12) - 1 "Year Last Day" FROM DUAL
Get number of days in current month
Now this is useful. This query returns number of days in current month. You can change SYSDATE with any date/value to know number of days in that month.
SELECT CAST (TO_CHAR (LAST_DAY (SYSDATE), 'dd') AS INT) number_of_days
FROM DUAL;
Get number of days left in current month
Below query calculates number of days left in current month.
SELECT SYSDATE,
LAST_DAY (SYSDATE) "Last",
LAST_DAY (SYSDATE) - SYSDATE "Days left"
FROM DUAL;
Get number of days between two dates
Use this query to get difference between two dates in number of days.
SELECT ROUND ( (MONTHS_BETWEEN ('01-Feb-2014', '01-Mar-2012') * 30), 0)
num_of_days
FROM DUAL;
OR
SELECT TRUNC(sysdate) - TRUNC(e.hire_date) FROM employees;
Use second query if you need to find number of days since some specific date. In this example number of days since any employee is hired.
Display each months start and end date upto last month of the year
This clever query displays start date and end date of each month in current year. You might want to use this for certain types of calculations.
SELECT ADD_MONTHS (TRUNC (SYSDATE, 'MONTH'), i) start_date,
TRUNC (LAST_DAY (ADD_MONTHS (SYSDATE, i))) end_date
FROM XMLTABLE (
'for $i in 0 to xs:int(D) return $i'
PASSING XMLELEMENT (
d,
FLOOR (
MONTHS_BETWEEN (
ADD_MONTHS (TRUNC (SYSDATE, 'YEAR') - 1, 12),
SYSDATE)))
COLUMNS i INTEGER PATH '.');
Get number of seconds passed since today (since 00:00 hr)
SELECT (SYSDATE - TRUNC (SYSDATE)) * 24 * 60 * 60 num_of_sec_since_morning
FROM DUAL;
Get number of seconds left today (till 23:59:59 hr)
SELECT (TRUNC (SYSDATE+1) - SYSDATE) * 24 * 60 * 60 num_of_sec_left
FROM DUAL;
Check if a table exists in the current database schema
A simple query that can be used to check if a table exists before you create it. This way you can make your create table script rerunnable. Just replace table_name with actual table you want to check. This query will check if table exists for current user (from where the query is executed).
SELECT table_name
FROM user_tables
WHERE table_name = 'TABLE_NAME';
Check if a column exists in a table
Simple query to check if a particular column exists in table. Useful when you tries to add new column in table using ALTER TABLE statement, you might wanna check if column already exists before adding one.
SELECT column_name AS FOUND
FROM user_tab_cols
WHERE table_name = 'TABLE_NAME' AND column_name = 'COLUMN_NAME';
How to retrieve 2nd highest sal in each departement from emp and dept tables using GROUP BY?
SELECT e.DeptNo, MAX(e.Sal),d.DeptName Salary
FROM Emp e left outer join dept d ON e.DeptNo=d.DeptNo
WHERE e.Sal <
(SELECT MAX(Sal)
FROM Emp
WHERE DeptNo = e.DeptNo)
GROUP BY e.DeptNo,d.DeptName
Find the 3rd MAX and MIN salary in the emp table?
select distinct sal from emp e1 where 3 = (select count(distinct sal) from emp e2 where e1.sal <= e2.sal);
select distinct sal from emp e1 where 3 = (select count(distinct sal) from emp e2where e1.sal >= e2.sal);
If there are two tables emp1 and emp2, and both have common record. How can I fetch all the records but common records only once?
(Select * from emp) Union (Select * from emp1)
How to fetch only common records from two tables emp and emp1?
(Select * from emp) Intersect (Select * from emp1)
How can I retrive all records of emp1 those should not present in emp2?
(Select * from emp) Minus (Select * from emp1)
Get the first day of the month?
Quickly returns the first day of current month. Instead of current month you want to find first day of month where a date falls, replace SYSDATE with any date column/value.
SELECT TRUNC (SYSDATE, 'MONTH') "First day of current month"
FROM DUAL;
Get the last day of the month?
This query is similar to above but returns last day of current month. One thing worth noting is that it automatically takes care of leap year. So if you have 29 days in Feb, it will return 29/2. Also similar to above query replace SYSDATE with any other date column/value to find last day of that particular month.
SELECT TRUNC (LAST_DAY (SYSDATE)) "Last day of current month"
FROM DUAL;
Get the first day of the Year
First day of year is always 1-Jan. This query can be use in stored procedure where you quickly want first day of year for some calculation.
SELECT TRUNC (SYSDATE, 'YEAR') "Year First Day" FROM DUAL;
Get the last day of the year
Similar to above query. Instead of first day this query returns last day of current year.
SELECT ADD_MONTHS (TRUNC (SYSDATE, 'YEAR'), 12) - 1 "Year Last Day" FROM DUAL
 |
| Oracle SQL Queries Most Frequently Asked In Huawei Written Test Interview |
Get number of days in current month
Now this is useful. This query returns number of days in current month. You can change SYSDATE with any date/value to know number of days in that month.
SELECT CAST (TO_CHAR (LAST_DAY (SYSDATE), 'dd') AS INT) number_of_days
FROM DUAL;
Get number of days left in current month
Below query calculates number of days left in current month.
SELECT SYSDATE,
LAST_DAY (SYSDATE) "Last",
LAST_DAY (SYSDATE) - SYSDATE "Days left"
FROM DUAL;
Get number of days between two dates
Use this query to get difference between two dates in number of days.
SELECT ROUND ( (MONTHS_BETWEEN ('01-Feb-2014', '01-Mar-2012') * 30), 0)
num_of_days
FROM DUAL;
OR
SELECT TRUNC(sysdate) - TRUNC(e.hire_date) FROM employees;
Use second query if you need to find number of days since some specific date. In this example number of days since any employee is hired.
Display each months start and end date upto last month of the year
This clever query displays start date and end date of each month in current year. You might want to use this for certain types of calculations.
SELECT ADD_MONTHS (TRUNC (SYSDATE, 'MONTH'), i) start_date,
TRUNC (LAST_DAY (ADD_MONTHS (SYSDATE, i))) end_date
FROM XMLTABLE (
'for $i in 0 to xs:int(D) return $i'
PASSING XMLELEMENT (
d,
FLOOR (
MONTHS_BETWEEN (
ADD_MONTHS (TRUNC (SYSDATE, 'YEAR') - 1, 12),
SYSDATE)))
COLUMNS i INTEGER PATH '.');
Get number of seconds passed since today (since 00:00 hr)
SELECT (SYSDATE - TRUNC (SYSDATE)) * 24 * 60 * 60 num_of_sec_since_morning
FROM DUAL;
Get number of seconds left today (till 23:59:59 hr)
SELECT (TRUNC (SYSDATE+1) - SYSDATE) * 24 * 60 * 60 num_of_sec_left
FROM DUAL;
Check if a table exists in the current database schema
A simple query that can be used to check if a table exists before you create it. This way you can make your create table script rerunnable. Just replace table_name with actual table you want to check. This query will check if table exists for current user (from where the query is executed).
SELECT table_name
FROM user_tables
WHERE table_name = 'TABLE_NAME';
Check if a column exists in a table
Simple query to check if a particular column exists in table. Useful when you tries to add new column in table using ALTER TABLE statement, you might wanna check if column already exists before adding one.
SELECT column_name AS FOUND
FROM user_tab_cols
WHERE table_name = 'TABLE_NAME' AND column_name = 'COLUMN_NAME';
Write a query to find the total sales of each product.?
Solution:
This is a simple query. You just need to group by the data on PRODUCT_NAME and then find the sum of sales.
SELECT P.PRODUCT_NAME,
NVL( SUM( S.QUANTITY*S.PRICE ), 0) TOTAL_SALES
FROM PRODUCTS P
LEFT OUTER JOIN
SALES S
ON (P.PRODUCT_ID = S.PRODUCT_ID)
GROUP BY P.PRODUCT_NAME;
Write a query to find the products whose quantity sold in a year should be greater than the average quantity of the product sold across all the years?
Solution:
This can be solved with the help of correlated query. The SQL query for this is
SELECT P.PRODUCT_NAME,
S.YEAR,
S.QUANTITY
FROM PRODUCTS P,
SALES S
WHERE P.PRODUCT_ID = S.PRODUCT_ID
AND S.QUANTITY >
(SELECT AVG(QUANTITY)
FROM SALES S1
WHERE S1.PRODUCT_ID = S.PRODUCT_ID
);
Write a query to compare the products sales of "IPhone" and "Samsung" in each year? The output should look like as
YEAR IPHONE_QUANT SAM_QUANT IPHONE_PRICE SAM_PRICE
---------------------------------------------------
2010 10 20 9000 7000
2011 15 18 9000 7000
2012 20 20 9000 7000
Solution:
By using self-join SQL query we can get the required result. The required SQL query is
SELECT S_I.YEAR,
S_I.QUANTITY IPHONE_QUANT,
S_S.QUANTITY SAM_QUANT,
S_I.PRICE IPHONE_PRICE,
S_S.PRICE SAM_PRICE
FROM PRODUCTS P_I,
SALES S_I,
PRODUCTS P_S,
SALES S_S
WHERE P_I.PRODUCT_ID = S_I.PRODUCT_ID
AND P_S.PRODUCT_ID = S_S.PRODUCT_ID
AND P_I.PRODUCT_NAME = 'IPhone'
AND P_S.PRODUCT_NAME = 'Samsung'
AND S_I.YEAR = S_S.YEAR
Write a query to find the ratios of the sales of a product?
Solution:
The ratio of a product is calculated as the total sales price in a particular year divide by the total sales price across all years. Oracle provides RATIO_TO_REPORT analytical function for finding the ratios. The SQL query is
SELECT P.PRODUCT_NAME,
S.YEAR,
RATIO_TO_REPORT(S.QUANTITY*S.PRICE)
OVER(PARTITION BY P.PRODUCT_NAME ) SALES_RATIO
FROM PRODUCTS P,
SALES S
WHERE (P.PRODUCT_ID = S.PRODUCT_ID);
In the SALES table quantity of each product is stored in rows for every year. Now write a query to transpose the quantity for each product and display it in columns? The output should look like as
PRODUCT_NAME QUAN_2010 QUAN_2011 QUAN_2012
------------------------------------------
IPhone 10 15 20
Samsung 20 18 20
Nokia 25 16 8
Solution:
Oracle 11g provides a pivot function to transpose the row data into column data. The SQL query for this is
SELECT * FROM
(
SELECT P.PRODUCT_NAME,
S.QUANTITY,
S.YEAR
FROM PRODUCTS P,
SALES S
WHERE (P.PRODUCT_ID = S.PRODUCT_ID)
)A
PIVOT ( MAX(QUANTITY) AS QUAN FOR (YEAR) IN (2010,2011,2012));
If you are not running oracle 11g database, then use the below query for transposing the row data into column data.
SELECT P.PRODUCT_NAME,
MAX(DECODE(S.YEAR,2010, S.QUANTITY)) QUAN_2010,
MAX(DECODE(S.YEAR,2011, S.QUANTITY)) QUAN_2011,
MAX(DECODE(S.YEAR,2012, S.QUANTITY)) QUAN_2012
FROM PRODUCTS P,
SALES S
WHERE (P.PRODUCT_ID = S.PRODUCT_ID)
GROUP BY P.PRODUCT_NAME;
Solution:
This is a simple query. You just need to group by the data on PRODUCT_NAME and then find the sum of sales.
SELECT P.PRODUCT_NAME,
NVL( SUM( S.QUANTITY*S.PRICE ), 0) TOTAL_SALES
FROM PRODUCTS P
LEFT OUTER JOIN
SALES S
ON (P.PRODUCT_ID = S.PRODUCT_ID)
GROUP BY P.PRODUCT_NAME;
Write a query to find the products whose quantity sold in a year should be greater than the average quantity of the product sold across all the years?
Solution:
This can be solved with the help of correlated query. The SQL query for this is
SELECT P.PRODUCT_NAME,
S.YEAR,
S.QUANTITY
FROM PRODUCTS P,
SALES S
WHERE P.PRODUCT_ID = S.PRODUCT_ID
AND S.QUANTITY >
(SELECT AVG(QUANTITY)
FROM SALES S1
WHERE S1.PRODUCT_ID = S.PRODUCT_ID
);
Write a query to compare the products sales of "IPhone" and "Samsung" in each year? The output should look like as
YEAR IPHONE_QUANT SAM_QUANT IPHONE_PRICE SAM_PRICE
---------------------------------------------------
2010 10 20 9000 7000
2011 15 18 9000 7000
2012 20 20 9000 7000
Solution:
By using self-join SQL query we can get the required result. The required SQL query is
SELECT S_I.YEAR,
S_I.QUANTITY IPHONE_QUANT,
S_S.QUANTITY SAM_QUANT,
S_I.PRICE IPHONE_PRICE,
S_S.PRICE SAM_PRICE
FROM PRODUCTS P_I,
SALES S_I,
PRODUCTS P_S,
SALES S_S
WHERE P_I.PRODUCT_ID = S_I.PRODUCT_ID
AND P_S.PRODUCT_ID = S_S.PRODUCT_ID
AND P_I.PRODUCT_NAME = 'IPhone'
AND P_S.PRODUCT_NAME = 'Samsung'
AND S_I.YEAR = S_S.YEAR
Write a query to find the ratios of the sales of a product?
Solution:
The ratio of a product is calculated as the total sales price in a particular year divide by the total sales price across all years. Oracle provides RATIO_TO_REPORT analytical function for finding the ratios. The SQL query is
SELECT P.PRODUCT_NAME,
S.YEAR,
RATIO_TO_REPORT(S.QUANTITY*S.PRICE)
OVER(PARTITION BY P.PRODUCT_NAME ) SALES_RATIO
FROM PRODUCTS P,
SALES S
WHERE (P.PRODUCT_ID = S.PRODUCT_ID);
In the SALES table quantity of each product is stored in rows for every year. Now write a query to transpose the quantity for each product and display it in columns? The output should look like as
PRODUCT_NAME QUAN_2010 QUAN_2011 QUAN_2012
------------------------------------------
IPhone 10 15 20
Samsung 20 18 20
Nokia 25 16 8
Solution:
Oracle 11g provides a pivot function to transpose the row data into column data. The SQL query for this is
SELECT * FROM
(
SELECT P.PRODUCT_NAME,
S.QUANTITY,
S.YEAR
FROM PRODUCTS P,
SALES S
WHERE (P.PRODUCT_ID = S.PRODUCT_ID)
)A
PIVOT ( MAX(QUANTITY) AS QUAN FOR (YEAR) IN (2010,2011,2012));
If you are not running oracle 11g database, then use the below query for transposing the row data into column data.
SELECT P.PRODUCT_NAME,
MAX(DECODE(S.YEAR,2010, S.QUANTITY)) QUAN_2010,
MAX(DECODE(S.YEAR,2011, S.QUANTITY)) QUAN_2011,
MAX(DECODE(S.YEAR,2012, S.QUANTITY)) QUAN_2012
FROM PRODUCTS P,
SALES S
WHERE (P.PRODUCT_ID = S.PRODUCT_ID)
GROUP BY P.PRODUCT_NAME;
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