Check anagrams using sql server - sql

Question

ACT and CAT are anagrams
I have to Write a function in sql server that takes 2 strings and given a Boolean output that indicates whether the both of them are anagram or not.
This doesnt make sense to do it in sql server,but,it is for learning purpose only

Answer 1

SQL Server is not good at this kind of things, but here you are:
WITH Src AS
(
SELECT * FROM (VALUES
('CAT', 'ACT'),
('CAR', 'RAC'),
('BUZ', 'BUS'),
('FUZZY', 'MUZZY'),
('PACK', 'PACKS'),
('AA', 'AA'),
('ABCDEFG', 'GFEDCBA')) T(W1, W2)
), Numbered AS
(
SELECT *, ROW_NUMBER() OVER (ORDER BY (SELECT 1)) Num
FROM Src
), Splitted AS
(
SELECT Num, W1 Word1, W2 Word2, LEFT(W1, 1) L1, LEFT(W2, 1) L2, SUBSTRING(W1, 2, LEN(W1)) W1, SUBSTRING(W2, 2, LEN(W2)) W2
FROM Numbered
UNION ALL
SELECT Num, Word1, Word2, LEFT(W1, 1) L1, LEFT(W2, 1) L2, SUBSTRING(W1, 2, LEN(W1)) W1, SUBSTRING(W2, 2, LEN(W2)) W2
FROM Splitted
WHERE LEN(W1)>0 AND LEN(W2)>0
), SplitOrdered AS
(
SELECT *,
ROW_NUMBER() OVER (PARTITION BY Num ORDER BY L1) LNum1,
ROW_NUMBER() OVER (PARTITION BY Num ORDER BY L2) LNum2
FROM Splitted
)
SELECT S1.Num, S1.Word1, S1.Word2, CASE WHEN COUNT(*)=LEN(S1.Word1) AND COUNT(*)=LEN(S1.Word2) THEN 1 ELSE 0 END Test
FROM SplitOrdered S1
JOIN SplitOrdered S2 ON S1.L1=S2.L2 AND S1.Num=S2.Num AND S1.LNum1=S2.LNum2
GROUP BY S1.Num, S1.Word1, S1.Word2
And results:
1 CAT ACT 1
2 CAR RAC 1
3 BUZ BUS 0
4 FUZZY MUZZY 0
5 PACK PACKS 0
6 AA AA 1
7 ABCDEFG GFEDCBA 1

Answer 2

First split (T-SQL Split Word into characters) both words into temporary tables. Then perform an outer join and check for nulls.
Edit thanks to George's comment:
split (T-SQL Split Word into characters) both words into temporary tables
Modify temporary tables or use CTEs to add a column with count(*) with group by letters clause
Perform a full outer join on two temporary tables using a letter and it's count in join condition
Check for nulls in the output - if there are none, you have an anagram

Answer 3

The first get in my mind:
DECLARE #word1 nvarchar(max) = NULL,
#word2 nvarchar(max) = 'Test 1',
#i int = 0, #n int
DECLARE #table TABLE (
id int,
letter int
)
SELECT #word1 = ISNULL(LOWER(#word1),''), #word2 = ISNULL(LOWER(#word2),'')
SELECT #n = CASE WHEN LEN(#word1) > LEN(#word2) THEN LEN(#word1) ELSE LEN(#word2) END
WHILE #n > 0
BEGIN
INSERT INTO #table
SELECT 1, ASCII(SUBSTRING(#word1,#n,1))
UNION ALL
SELECT 2, ASCII(SUBSTRING(#word2,#n,1))
SET #n=#n-1
END
SELECT CASE WHEN COUNT(*) = 0 THEN 1 ELSE 0 END isAnagram
FROM (
SELECT id, letter, COUNT(letter) as c
FROM #table
WHERE id = 1
GROUP BY id, letter)as t
FULL OUTER JOIN (
SELECT id, letter, COUNT(letter) as c
FROM #table
WHERE id = 2
GROUP BY id, letter) as p
ON t.letter = p.letter and t.c =p.c
WHERE t.letter is NULL OR p.letter is null
Output:
isAnagram
0

Answer 4

You can also use loops in functions, and they can work fast. I am not able to get any of the of other answers even close to the performance of this function:
CREATE FUNCTION IsAnagram
(
#value1 VARCHAR(255)
, #value2 VARCHAR(255)
)
RETURNS BIT
BEGIN
IF(LEN(#value1) != LEN(#value2))
RETURN 0;
DECLARE #firstChar VARCHAR(3);
WHILE (LEN(#value1) > 0)
BEGIN
SET #firstChar = CONCAT('%', LEFT(#value1, 1), '%');
IF(PATINDEX(#firstChar, #value2) > 0)
SET #value2 = STUFF(#value2, PATINDEX(#firstChar, #value2), 1, '');
ELSE
RETURN 0;
SET #value1 = STUFF(#value1, 1, 1, '');
END
RETURN (SELECT IIF(#value2 = '', 1, 0));
END
GO
SELECT dbo.IsAnagram('asd', 'asd')
--1
SELECT dbo.IsAnagram('asd', 'dsa')
--1
SELECT dbo.IsAnagram('assd', 'dsa')
--0
SELECT dbo.IsAnagram('asd', 'dssa')
--0
SELECT dbo.IsAnagram('asd', 'asd')

Answer 5

This is something a numbers table can help with.
Code to create and populate a small numbers table is below.
CREATE TABLE dbo.Numbers
(
Number INT PRIMARY KEY
);
WITH Ten(N) AS
(
SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL
SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL
SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1
)
INSERT INTO dbo.Numbers
SELECT ROW_NUMBER() OVER (ORDER BY ##SPID) AS Number
FROM Ten T10,
Ten T100,
Ten T1000
Once that is in place you can use
SELECT W1,
W2,
IsAnagram = CASE
WHEN LEN(W1) <> LEN(W2)
THEN 0
ELSE
CASE
WHEN EXISTS (SELECT SUBSTRING(W1, Number, 1),
COUNT(*)
FROM dbo.Numbers
WHERE Number <= LEN(W1)
GROUP BY SUBSTRING(W1, Number, 1)
EXCEPT
SELECT SUBSTRING(W2, Number, 1),
COUNT(*)
FROM dbo.Numbers
WHERE Number <= LEN(W2)
GROUP BY SUBSTRING(W2, Number, 1))
THEN 0
ELSE 1
END
END
FROM (VALUES
('CAT', 'ACT'),
('CAR', 'RAC'),
('BUZ', 'BUS'),
('FUZZY', 'MUZZY'),
('PACK', 'PACKS'),
('AA', 'AA'),
('ABCDEFG', 'GFEDCBA')) T(W1, W2)
Or an alternative implementation could be
IsAnagram = CASE
WHEN LEN(W1) <> LEN(W2)
THEN 0
ELSE
CASE
WHEN EXISTS (SELECT 1
FROM dbo.Numbers N
CROSS APPLY (VALUES(1,W1),
(2,W2)) V(Col, String)
WHERE N.Number <= LEN(W1)
GROUP BY SUBSTRING(String, Number, 1)
HAVING COUNT(CASE WHEN Col = 1 THEN 1 END) <>
COUNT(CASE WHEN Col = 2 THEN 1 END))
THEN 0
ELSE 1
END
END