Solution:
“LG” is the only product which does not have sales at all. This can be achieved in three ways.
Method 1: Using left outer join.
SELECT P.PRODUCT_NAME
FROM PRODUCTS P
LEFT OUTER JOIN
SALES S
ON (P.PRODUCT_ID = S.PRODUCT_ID);
WHERE S.QUANTITY IS NULL
PRODUCT_NAME
------------
LG
Method 2: Using the NOT IN operator.
SELECT P.PRODUCT_NAME
FROM PRODUCTS P
WHERE P.PRODUCT_ID NOT IN
(SELECT DISTINCT PRODUCT_ID FROM SALES);
PRODUCT_NAME
------------
LG
Method 3: Using the NOT EXISTS operator.
SELECT P.PRODUCT_NAME
FROM PRODUCTS P
WHERE NOT EXISTS
(SELECT 1 FROM SALES S WHERE S.PRODUCT_ID = P.PRODUCT_ID);
PRODUCT_NAME
------------
LG
Write a SQL query to find the products whose sales decreased in 2012 compared to 2011?
Solution:
Here Nokia is the only product whose sales decreased in year 2012 when compared with the sales in the year 2011. The SQL query to get the required output is
SELECT P.PRODUCT_NAME
FROM PRODUCTS P,
SALES S_2012,
SALES S_2011
WHERE P.PRODUCT_ID = S_2012.PRODUCT_ID
AND S_2012.YEAR = 2012
AND S_2011.YEAR = 2011
AND S_2012.PRODUCT_ID = S_2011.PRODUCT_ID
AND S_2012.QUANTITY < S_2011.QUANTITY;
PRODUCT_NAME
------------
Nokia
Write a query to select the top product sold in each year?
Solution:
Nokia is the top product sold in the year 2010. Similarly, Samsung in 2011 and IPhone, Samsung in 2012. The query for this is
SELECT PRODUCT_NAME,
YEAR
FROM
(
SELECT P.PRODUCT_NAME,
S.YEAR,
RANK() OVER (
PARTITION BY S.YEAR
ORDER BY S.QUANTITY DESC
) RNK
FROM PRODUCTS P,
SALES S
WHERE P.PRODUCT_ID = S.PRODUCT_ID
) A
WHERE RNK = 1;
 |
| Oracle SQL Queries Most Frequently Asked In Baidu Written Test Interview |
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;
Write a query to find the number of products sold in each year?
Solution:
To get this result we have to group by on year and the find the count. The SQL query for this question is
SELECT YEAR,
COUNT(1) NUM_PRODUCTS
FROM SALES
GROUP BY YEAR;
Write a query to generate sequence numbers from 1 to the specified number N?
Solution:
SELECT LEVEL FROM DUAL CONNECT BY LEVEL<=&N;
Write a query to display only Sunday dates from Jan, 2000 to till now?
Solution:
SELECT C_DATE,
TO_CHAR(C_DATE,'DY')
FROM
(
SELECT TO_DATE('01-JAN-2000','DD-MON-YYYY')+LEVEL-1 C_DATE
FROM DUAL
CONNECT BY LEVEL <=
(SYSDATE - TO_DATE('01-JAN-2000','DD-MON-YYYY')+1)
)
WHERE TO_CHAR(C_DATE,'DY') = 'SUN';
Write a query to duplicate each row based on the value in the repeat column? The input table data looks like as below
Products, Repeat
----------------
A, 3
B, 5
C, 2
Now in the output data, the product A should be repeated 3 times, B should be repeated 5 times and C should be repeated 2 times. The output will look like as below
Products, Repeat
----------------
A, 3
A, 3
A, 3
B, 5
B, 5
B, 5
B, 5
B, 5
C, 2
C, 2
Solution:
SELECT PRODUCTS,
REPEAT
FROM T,
( SELECT LEVEL L FROM DUAL
CONNECT BY LEVEL <= (SELECT MAX(REPEAT) FROM T)
) A
WHERE T.REPEAT >= A.L
ORDER BY T.PRODUCTS;
Write a query to display each letter of the word "BIG" in a separate row?
B
I
G
Solution:
SELECT SUBSTR('SMILE',LEVEL,1) A
FROM DUAL
CONNECT BY LEVEL <=LENGTH('BIG');
Convert the string "SMILE" to Ascii values? The output should look like as 83,77,73,76,69. Where 83 is the ascii value of S and so on.
The ASCII function will give ascii value for only one character. If you pass a string to the ascii function, it will give the ascii value of first letter in the string. Here i am providing two solutions to get the ascii values of string.
Solution 1:
SELECT SUBSTR(DUMP('SMILE'),15)
FROM DUAL;
Solution2:
SELECT WM_CONCAT(A)
FROM
(
SELECT ASCII(SUBSTR('SMILE',LEVEL,1)) A
FROM DUAL
CONNECT BY LEVEL <=LENGTH('SMILE')
);
Consider the following friends table as the source
Name, Friend_Name
-----------------
sam, ram
sam, vamsi
vamsi, ram
vamsi, jhon
ram, vijay
ram, anand
Here ram and vamsi are friends of sam; ram and jhon are friends of vamsi and so on. Now write a query to find friends of friends of sam. For sam; ram,jhon,vijay and anand are friends of friends. The output should look as
Name, Friend_of_Firend
----------------------
sam, ram
sam, jhon
sam, vijay
sam, anand
Solution:
SELECT f1.name,
f2.friend_name as friend_of_friend
FROM friends f1,
friends f2
WHERE f1.name = 'sam'
AND f1.friend_name = f2.name;
In the output, you can see ram is displayed as friends of friends. This is because, ram is mutual friend of sam and vamsi. Now extend the above query to exclude mutual friends. The output should look as
Name, Friend_of_Friend
----------------------
sam, jhon
sam, vijay
sam, anand
Solution:
SELECT f1.name,
f2.friend_name as friend_of_friend
FROM friends f1,
friends f2
WHERE f1.name = 'sam'
AND f1.friend_name = f2.name
AND NOT EXISTS
(SELECT 1 FROM friends f3
WHERE f3.name = f1.name
AND f3.friend_name = f2.friend_name);