In this post, I am sharing one complex SQL Query interview question and solution for T-SQL Developers.

Last week, I asked this question to one of the T-SQL Developer.
If you are going for database developer interview, you must find and practice complex or advance SQL Queries.

Question: Find a count of given repeated character from a string

Create a table with sample data:

CREATE TABLE tbl_Strings (name VARCHAR(30))
GO

INSERT INTO tbl_Strings
VALUES
('India'),('Southern Europe')
,('Japan'),('Indonesia')
,('Swaziland'),('South Africa')
,('United Arab Emirates'),('United States')
GO

Solution:

;WITH CTE AS
(
		SELECT name, CONVERT(VARCHAR(1),LEFT(name,1)) AS Letter, RIGHT(name, LEN(name)-1) AS Remain
		FROM tbl_Strings
		WHERE LEN(name)>1
	UNION ALL
		SELECT name, CONVERT(VARCHAR(1),LEFT(Remain,1)) AS Letter, 
			RIGHT(Remain, LEN(Remain)-1) AS Remain
		FROM CTE
		WHERE LEN(Remain)>0
)
SELECT 
	name
	,Letter
	,ASCII(Letter) AS CharAsciiCode
	,COUNT(Letter) AS CountOfLetter
FROM CTE
WHERE Letter IN('a','A')
GROUP BY name, Letter, ASCII(Letter)

The Result:

name                           Letter CharAsciiCode CountOfLetter
------------------------------ ------ ------------- -------------
South Africa                   A      65            1
United Arab Emirates           A      65            1
India                          a      97            1
Indonesia                      a      97            1
Japan                          a      97            2
South Africa                   a      97            1
Swaziland                      a      97            2
United Arab Emirates           a      97            2
United States                  a      97            1