Count vowels and consonants in an array - function

Question

I am trying to write a function which will return number of vowels
and consonants. Using the IF statement function will successfully
compile, however when I call it in the select it shows the message :
"Conversion failed when converting the varchar value 'MAMAMIA' to
data type int."`
I tried with the CASE statement, but there are too many syntax
errors and i think it is not the best method of solving the problem
using CASE ...
CREATE FUNCTION VOW_CONS(#ARRAY VARCHAR(20))
RETURNS INT
BEGIN
DECLARE #COUNTT INT;
DECLARE #COUNTT1 INT;
SET #COUNTT=0;
SET #COUNTT1=0;
WHILE (#ARRAY!=0)
BEGIN
IF(#ARRAY LIKE '[aeiouAEIOU]%')
SET #COUNTT=#COUNTT+1
ELSE SET #COUNTT1=#COUNTT1+1
/*
DECLARE #C INT;
SET #C=(CASE #SIR WHEN 'A' THEN #COUNTT=#COUNTT+1;
WHEN 'E' THEN #COUNTT=#COUNTT+1
WHEN 'I' THEN #COUNTT=#COUNTT+1
WHEN 'O' THEN #COUNTT=#COUNTT+1
WHEN 'U' THEN #COUNTT=#COUNTT+1
WHEN 'A' THEN #COUNTT=#COUNTT+1
WHEN ' ' THEN ' '
ELSE #COUNTT1=#COUNTT1+1
END)
*/
END
RETURN #COUNTT;
END
SELECT DBO.VOW_CONS('MAMAMIA')

Answer 1

Without knowing what version of SQL Server you are using, I am going to assume you are using the latest version, meaning you have access to TRANSLATE. Also I'm going to assume you do need access to both the number of vowels and consonants, so a table-value function seems the better method here. As such, you could do something like this:
CREATE FUNCTION dbo.CountVowelsAndConsonants (#String varchar(20))
RETURNS table
AS RETURN
SELECT DATALENGTH(#String) - DATALENGTH(REPLACE(TRANSLATE(#String,'aeiou','|||||'),'|','')) AS Vowels, --Pipe is a character that can't be in your string
DATALENGTH(#String) - DATALENGTH(REPLACE(TRANSLATE(#String,'bcdfghjklmnpqrstvwxyz','|||||||||||||||||||||'),'|','')) AS Consonants --Pipe is a character that can't be in your string
GO
And then you can use the function like so:
SELECT *
FROM (VALUES('MAMAMIA'),('Knowledge is power'))V(YourString)
CROSS APPLY dbo.CountVowelsAndConsonents(V.YourString);

Answer 2

Another option would be to split the string into its individual letters using a tally table, join that to a table of vowels/consonants and then get your counts.
Here is a working example, you'll have to update/change for your specific needs but should give you an idea on how it works.
DECLARE #string NVARCHAR(100)
SET #string = 'Knowledge is power';
--Here we build a table of all the letters setting a flag on which ones are vowels
DECLARE #VowelConsonants TABLE
(
[Letter] CHAR(1)
, [IsVowel] BIT
);
--We load it with the data
INSERT INTO #VowelConsonants (
[Letter]
, [IsVowel]
)
VALUES ( 'a', 1 ) , ( 'b', 0 ) , ( 'c', 0 ) , ( 'd', 0 ) , ( 'e', 1 ) , ( 'f', 0 ) , ( 'g', 0 ) , ( 'h', 0 ) , ( 'i', 1 ) , ( 'j', 0 ) , ( 'k', 0 ) , ( 'l', 0 ) , ( 'm', 0 ) , ( 'n', 0 ) , ( 'o', 1 ) , ( 'p', 0 ) , ( 'q', 0 ) , ( 'r', 0 ) , ( 's', 0 ) , ( 't', 0 ) , ( 'u', 1 ) , ( 'v', 0 ) , ( 'w', 0 ) , ( 'x', 0 ) , ( 'y', 0 ) , ( 'z', 0 );
--This tally table example gives 10,000 numbers
WITH
E1(N) AS (select 1 from (values (1),(1),(1),(1),(1),(1),(1),(1),(1),(1))dt(n)),
E2(N) AS (SELECT 1 FROM E1 a, E1 b), --10E+2 or 100 rows
E4(N) AS (SELECT 1 FROM E2 a, E2 b), --10E+4 or 10,000 rows max
cteTally(N) AS
(
SELECT ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) FROM E4
)
SELECT SUM( CASE WHEN [vc].[IsVowel] = 1 THEN 1
ELSE 0
END
) AS [VowelCount]
, SUM( CASE WHEN [vc].[IsVowel] = 0 THEN 1
ELSE 0
END
) AS [ConsonantCount]
FROM [cteTally] [t] --Select from tally cte
INNER JOIN #VowelConsonants [vc] --Join to VowelConsonants table on the letter.
ON LOWER([vc].[Letter]) = LOWER(SUBSTRING(#string, [t].[N], 1)) --Using the number from the tally table we can easily split out each letter using substring
WHERE [t].[N] <= LEN(#string);
Giving you results of:
VowelCount ConsonantCount
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