MySql匹配最特定的人的名字

Question

I am searching a MySql table for the likely match for a specific person. I am using lots of other criteria but assume we are just talking about the given names field.

Say the search value is John William and the table contains 4 rows with name values

John
John William 
John William Henry
John Paul 

The first 3 could be the right person. I want the search to return the one with the closest match to the name I have, which in this case is row 2.

The original code first does an exact match query using the full supplied name(s). If that returns no records it then does a LIKE query using all names with % on the end. If that fails it then does an exact search on the first name only. In the above example the first query returns record 2 which is what is wanted so the other queries are not run.

The problem is if the search name is John William Henry George, you potentially have to do about 5 queries to gradually make the search less specific. The other problem is that the search value could be John W and the file could contain John William which I would want to match. Or vice versa.

Is there some way of doing a single query that will return the closest match please? In other words that will return just row 2 in the above example.

In order of best fit this is what I think a search for John William Henry should match:

John William Henry
John William Henry %
John William H
John William H %
John W H
John W H %
John W
John

Note that there is no % after the John W because that will match John WB who cannot be the right person.

Ok, new idea to try to make it more efficient. Is it possible to query the results of a previous query with some PHP code in between. I expect not. Pseudo code as follows:

$coarse = Mysql search for John%
$count = mysql_num_rows($coarse);
if ($count == 1) { 
   $rec = mysql_fetch_row($coarse);
   return $rec[0];
} 
// Assume that produced 50 records. Now want to search within those only instead of millions

$fine = Mysql search within $coarse results for John William% 
$count = mysql_num_rows($fine);
if ($count == 1) { 
   $rec = mysql_fetch_row($fine);
   return $rec[0];
} 

I could obviously do the fine search in PHP but is it possible to do it in SQL, or can I maybe do the above with a stored procedure?

Answer 1

I'd create a stored procedure. Use an IF ELSE, check if EXISTS then use NOT IN to exclude the entries of Query 1.

Note: There is an EXCEPT operator in ANSI SQL but MySQL doesn't support it so you'd use NOT IN to exclude rows of query 1.

Also don't put too much logic in the database/SQL... if you want to get fancy with your name matching I'd select a basic list of matches with SQL then use PHP code (with regular expressions) for the 'fuzzy/best' match or logic.

Answer 2

CREATE PROCEDURE (@u varchar(max))
    BEGIN
        SET @v_counter = CHAR_LENGTH(@u);
        while @v_counter >0 do
            if (Select count(*) from table where firstName like @u+"%")>0
                @v_counter=0
            else
                Begin
                   @u=substr(@u, 0, -1)
                   @v_counter=char_length(u)
                END            
         end while
SELECT * from table where firstName like @u+"%"
Return
END;

This is untested, but should get you where you want to go. It is a procedure that should start with the full name and remove one character at a time to check for the first matching results.

Answer 3

Maybe try a different approach. Have a look into MySQLs fulltext search capabilities .

Let me give you an easy example to begin with. Lets say your table looks like this:

 CREATE TABLE people (
     id INT UNSIGNED AUTO_INCREMENT NOT NULL PRIMARY KEY,
     fullname TEXT,
     FULLTEXT (fullname)
 ) ENGINE=InnoDB;

Then you can query it like this:

SELECT *, 
    MATCH (fullname) AGAINST ('+John William' IN BOOLEAN MODE) AS 'Probability'
FROM people
WHERE MATCH (fullname)
AGAINST ('+John William' IN BOOLEAN MODE)
ORDER BY Probability DESC;

The operators might have to be slightly altered in order to get your desired result.

Keep in mind, for using fulltext indexes on InnoDB you need a newer version of MySQL. If this is not available, you have to use MyISAM as engine.

Answer 4

我认为最简单的方法是简单地进行搜索，从最具体的开始到最不具体的搜索。