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T-SQL Query | [ The Remove Nulls Puzzle ]
Puzzle Description
There was a question Its very easy you just have to remove the nulls from the different cities. Check out the input and expected output below-
Pictorial presentation of the puzzle.(Pic taken from some Facebook group)
Pawan Khowal – The RemoveNull Puzzle
Sample Input
| ID | Name | Salary | City1 | City2 | City3 |
| 1 | A | 100 | Bangalore | NULL | NULL |
| 1 | B | 200 | NULL | Pune | NULL |
| 1 | C | 300 | NULL | NULL | Hyderabad |
Expected Output
| Id | Name | Salary | City1 | City2 | City3 |
| 1 | A | 100 | Bangalore | Pune | Hyderabad |
Rules/Restrictions
- The solution should be should use “SELECT” statement or “CTE”.
- Add your solution(s) in the comments section or send you solution(s) topawankkmr@gmail.com
Script
Use the below script to generate the source table and fill them up with the sample data.
-- CREATE TABLE RemoveNulls ( ID INT ,Name VARCHAR(1) ,Salary INT ,City1 VARCHAR(50) ,City2 VARCHAR(50) ,City3 VARCHAR(50) ) GO INSERT INTO RemoveNulls(ID,Name,Salary,City1,City2,City3) VALUES (1,'A',100,'Bangalore',NULL,NULL),(1,'B',200,NULL,'Pune',NULL),(1,'C',300,NULL,NULL,'Hyderabad') GO CREATE CLUSTERED INDEX Ix_Id ON RemoveNulls(Id) GO -- |
Update Aug 06 | Solution1 & 2 – Pawan Kumar Khowal
--
--Solution1
SELECT *
, ( SELECT TOP 1 City2 FROM RemoveNulls r1 WHERE r1.City2 IS NOT NULL AND r1.ID = X.ID ) City2
, ( SELECT TOP 1 City3 FROM RemoveNulls r1 WHERE r1.City3 IS NOT NULL AND r1.ID = X.ID ) City3
FROM
(
SELECT r.ID,MIN(Name) Name,MIN(Salary) Salary ,MIN(City1) City1
FROM RemoveNulls r
WHERE City1 IS NOT NULL
GROUP BY ID
)X
--Solution 2
SELECT
Id
, MIN(name) Name
, MIN(Salary) Salary
, MAX(city1) City1
, MAX(city2) City2
, MAX(city3) City3
FROM RemoveNulls GROUP BY id
--
|
Add a comment if you have any other solution in mind. We all need to learn. Keep Learning
Http://MSBISkills.com
Pawan Kumar Khowal
Improving my SQL BI Skills 
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