October 6, 2018

Sreekanth B

Birlasoft Frequently Asked Oracle SQL Queries In Written Test Interview Questions

Write a SQL query to find the products which does not have sales at all?

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;

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;
Birlasoft Frequently Asked Oracle SQL Queries In Written Test Interview Questions
Birlasoft Frequently Asked Oracle SQL Queries In Written Test Interview Questions

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')
);

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