Question

I am trying to do a ‘fuzzy’ search on a sql table with names of people:

This is the table:

+----+------------+
| T1 | T2         |
+----+------------+
| 1  | Last,First |
| 2  | Last,First |
| 3  | Last,First |
+----+------------+

I want to get a select statement where I query T2 with the LIKE operator such that it works even when your query is “First Last”

The only way I can think of is by splitting the values and concatenating them and then searching again for the entry. Is there a better way to do this?

Answer 1

Yes, if there’s a possibility you may put both last, first and first last into the database, the better way is to design your schema properly.

If you ever find yourself trying to search on, or otherwise manipulate, parts of columns, your schema is almost certainly broken. It will almost certainly kill performance.

The correct way is to have the table thus:

T1  FirstName  LastName
==  =========  ========
 1  Pax        Diablo
 2  Bob        Smith
 3  George     Jones

Then you can more efficiently split the user-entered name (once, before running the query) rather than trying to split every single name in the database.

---

In the case where the database always holds last, first, it may not actually be necessary for a schema change.

The problem you have in that case is simply one of interpreting what the user entered.

One possibility, although it is a performance killer, is to do a like for each separate word. So, if the user entered pax diablo, your resultant query might be:

select T1 from mytable
    where T2 like '%pax%'
      and T2 like '%diablo%'

That way, you don’t care about the order so much.

However, given my dislike of slow queries, I’d try to steer clear of that unless absolutely necessary (or your database is relatively small and likely to stay that way).

There are all sorts of ways to speed up these sorts of queries, such as:

• using whatever full-text search capabilities your DBMS has.
• emulating such abilities by extracting and storing words during insert/update triggers (and removing them during delete triggers).
• that previous case, but also ensuring extra columns used with lower-cased values of the current column (for speed).
• telling the user they need to use the last, first form for searching.
• trying to avoid the %something% search string as much as possible (with something%, indexes can still be used).
• my previously mentioned “split th name into two columns” method.