Change the casing of my letters in string using sql function - sql

Question

I want to convert my string into opposite casing in sql using function.
can someone help me??
I am able to do the first letter of the string but not middle letters
http://www.sql-server-helper.com/functions/initcap.aspx
Example:
input:
"hI mY Name IS Joe"
output:
"Hi My nAME is jOE"

Answer 1

If your sql-server version support (sql-server-2017 and above), you can use TRANSLATE function
SELECT TRANSLATE ('hI mY Name IS Joe' COLLATE Latin1_general_CS_AS
,'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz'
,'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ')
Result:
Hi My nAME is jOE

Answer 2

A completely set-based approach:
DECLARE #TheLinkTable TABLE(ID INT IDENTITY,YourText NVARCHAR(1000));
INSERT INTO #TheLinkTable VALUES('hI mY Name IS Joe');
The query:
WITH cte AS
(
SELECT t.ID
,t.YourText
,A.Nmbr
,C.SwitchedLetter
FROM #TheLinkTable t
CROSS APPLY(SELECT TOP(LEN(t.YourText)) ROW_NUMBER() OVER(ORDER BY (SELECT NULL)) FROM master..spt_values) A(Nmbr)
CROSS APPLY(SELECT SUBSTRING(t.YourText,A.Nmbr,1)) B(TheLetter)
CROSS APPLY(SELECT CASE WHEN TheLetter LIKE '[a-zA-Z]'
THEN CHAR(ASCII(TheLetter) ^ 0x20)
ELSE CASE WHEN TheLetter=' ' THEN TheLetter END END) C(SwitchedLetter)
)
SELECT cte1.ID
,cte1.YourText
,(
SELECT SwitchedLetter AS [*]
FROM cte cte2
WHERE cte2.ID=cte1.ID
ORDER BY cte2.Nmbr
FOR XML PATH(''),TYPE).value('.','nvarchar(max)'
)
FROM cte cte1
GROUP BY cte1.ID,cte1.YourText;
The idea in short:
Using a tally-on-the-fly (in this case a ROW_NUMBER() against any bigger set with a computed TOP-clause we get a running number from 1 to n where n is the count of letters.
The second APPLY will pick each letter separately.
The third apply will switch the casing of letters from a to z simply by XORing the binary representation and re-set the significant BIT. A blank is returned as is.
The following SELECT will group by the ID and use a correlated sub-query to reconcatenate the string.
Another set-based approach implies a recursive CTE:
WITH recCTE AS
(
SELECT 1 AS position
,YourText
,CAST(CASE WHEN ASCII(TheLetter) BETWEEN 65 AND 90 THEN LOWER(TheLetter)
ELSE CASE WHEN ASCII(TheLetter) BETWEEN 97 AND 122 THEN UPPER(TheLetter) END END AS NVARCHAR(MAX)) AS SwitchLetter
FROM #TheLinkTable
CROSS APPLY(SELECT SUBSTRING(YourText,1,1)) A(TheLetter)
UNION ALL
SELECT r.position+1
,YourText
,CONCAT(r.SwitchLetter
,CASE WHEN ASCII(TheLetter) BETWEEN 65 AND 90 THEN LOWER(TheLetter)
ELSE CASE WHEN ASCII(TheLetter) BETWEEN 97 AND 122 THEN UPPER(TheLetter)
ELSE TheLetter END END) AS SwitchLetter
FROM recCTE r
CROSS APPLY(SELECT SUBSTRING(YourText,r.position+1,1)) A(TheLetter)
WHERE r.position<LEN(YourText)
)
SELECT * FROM recCte;
You must add a WHERE to pick the last one (e.g. LEN(SwitchLetter)=LEN(YourText)). I left it aside to show how it's working.