DIFFERENCE (Transact-SQL)

character_expression

Is an alphanumeric expression of character data. character_expression can be a constant, variable, or column.

int

The integer returned is the number of characters in the SOUNDEX values that are the same. The return value ranges from 0 through 4: 0 indicates weak or no similarity, and 4 indicates strong similarity or the same values.

DIFFERENCE and SOUNDEX are collation sensitive.

In the first part of the following example, the SOUNDEX values of two very similar strings are compared. For a Latin1_General collation DIFFERENCE returns a value of 4. In the second part of the following example, the SOUNDEX values for two very different strings are compared, and for a Latin1_General collation DIFFERENCE returns a value of 0.

USE AdventureWorks2012;
GO
-- Returns a DIFFERENCE value of 4, the least possible difference.
SELECT SOUNDEX('Green'), SOUNDEX('Greene'), DIFFERENCE('Green','Greene');
GO
-- Returns a DIFFERENCE value of 0, the highest possible difference.
SELECT SOUNDEX('Blotchet-Halls'), SOUNDEX('Greene'), DIFFERENCE('Blotchet-Halls', 'Greene');
GO

Here is the result set.

----- ----- ----------- 
G650  G650  4           

(1 row(s) affected)
                        
----- ----- ----------- 
B432  G650  0           

(1 row(s) affected)

Reference