levenshtein distance in sqlserver
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CREATE FUNCTION [dbo].[LEVENSHTEIN]( @s NVARCHAR(MAX), @t NVARCHAR(MAX) ) | |
/* | |
Levenshtein Distance Algorithm: TSQL Implementation | |
by Joseph Gama | |
http://www.merriampark.com/ldtsql.htm | |
Returns the Levenshtein Distance between strings s1 and s2. | |
Original developer: Michael Gilleland http://www.merriampark.com/ld.htm | |
Translated to TSQL by Joseph Gama | |
Fixed by Herbert Oppolzer / devio | |
as described in https://devio.wordpress.com/2010/09/07/calculating-levenshtein-distance-in-tsql | |
*/ | |
RETURNS INT AS | |
BEGIN | |
DECLARE @d NVARCHAR(MAX), @LD INT, @m INT, @n INT, @i INT, @j INT, | |
@s_i NCHAR(1), @t_j NCHAR(1),@cost INT | |
--Step 1 | |
SET @n = LEN(@s) | |
SET @m = LEN(@t) | |
SET @d = REPLICATE(NCHAR(0),(@n+1)*(@m+1)) | |
IF @n = 0 | |
BEGIN | |
SET @LD = @m | |
GOTO done | |
END | |
IF @m = 0 | |
BEGIN | |
SET @LD = @n | |
GOTO done | |
END | |
--Step 2 | |
SET @i = 0 | |
WHILE @i <= @n BEGIN | |
SET @d = STUFF(@d,@i+1,1,NCHAR(@i)) --d(i, 0) = i | |
SET @i = @i+1 | |
END | |
SET @i = 0 | |
WHILE @i <= @m BEGIN | |
SET @d = STUFF(@d,@i*(@n+1)+1,1,NCHAR(@i)) --d(0, j) = j | |
SET @i = @i+1 | |
END | |
--Step 3 | |
SET @i = 1 | |
WHILE @i <= @n BEGIN | |
SET @s_i = SUBSTRING(@s,@i,1) | |
--Step 4 | |
SET @j = 1 | |
WHILE @j <= @m BEGIN | |
SET @t_j = SUBSTRING(@t,@j,1) | |
--Step 5 | |
IF @s_i = @t_j | |
SET @cost = 0 | |
ELSE | |
SET @cost = 1 | |
--Step 6 | |
SET @d = STUFF(@d,@j*(@n+1)+@i+1,1, | |
NCHAR(dbo.MIN3( | |
UNICODE(SUBSTRING(@d,@j*(@n+1)+@i-1+1,1))+1, | |
UNICODE(SUBSTRING(@d,(@j-1)*(@n+1)+@i+1,1))+1, | |
UNICODE(SUBSTRING(@d,(@j-1)*(@n+1)+@i-1+1,1))+@cost) | |
)) | |
SET @j = @j+1 | |
END | |
SET @i = @i+1 | |
END | |
--Step 7 | |
SET @LD = UNICODE(SUBSTRING(@d,@n*(@m+1)+@m+1,1)) | |
done: | |
RETURN @LD | |
END |
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create function [dbo].[min3](@a int, @b int, @c int) | |
returns int as | |
begin | |
declare @min int | |
set @min = @a | |
if @b < @min set @min = @b | |
if @c < @min set @min = @c | |
return @min | |
end |
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select a.nama,b.nama,dbo.LEVENSHTEIN(a.nama,b.nama) | |
from tabel1 a inner join tabel2 b on a.kde....b.kde...... |
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