advanced word searching in sql - sql

Question

i need to write a query in sql server which selects rows containing two word with (at least / at most / exactly) specified number of word between them ...
i wrote this code for implementing exact number of words in between :
SELECT simpledtext
FROM booktexts
WHERE simpledtext LIKE '%hello [^ ] [^ ] search%'
and this code for implementing minimum number of words in between :
SELECT simpledtext
FROM booktexts
WHERE simpledtext LIKE '%hello [^ ] [^ ] % search%'
but i don't know how to write the max words in between t-sql code ...
and the other question is is it possible to implement these kinds of query with full-text-search in sql server 2012 ?

Answer 1

Your like string would only match single character words. If this is what you need, you could put something together like this:
declare #str1 varchar(1024) = 'and hello w w w search how are you',
#str2 varchar(1024) = 'and hello w w search how are you',
#likeStr varchar(512),
#pos int,
#maxMatch int;
set #maxMatch = 2;
set #pos = 0;
set #likeStr = '%hello';
while (#pos < #maxMatch)
begin
set #likeStr += ' [^ ]';
set #pos += 1;
end
set #likeStr += ' search%';
select #likeStr, (case when #str1 like #likeStr then 1 else 0 end), (case when #str2 like #likeStr then 1 else 0 end)
If this isn't what you need, and you know how many characters the words are going to be, you could use [a-zA-Z] in the like string in the loop.
However, I expect this also will not be what you're after. My suggestion would then be to abandon like strings, and move on to the more sophisticated regular expressions.
Unfortunately you can't load System.dll directly into SQL Server 2008 (I think this also applies to SQL Server 2012), so you would need to create a custom .NET assembly and load this into your database. Your should use the IsDeterministic annotation in your .NET code, and load the custom assembly into SQL Server with permission_set = safe. This should ensure you get parallelism for your function, and that you can use it in places like computed columns.
SQL Server is very good at running .NET code, i.e. it can be very
performant. Writing what you need in regular expressions should be
very easy.
As for Full Text Search, contains() is basically a Full Text predicate, and you would have to enable this in SQL Server to use it. near() is used inside contains() predicates. I think this is bulky for what you want to do, both in terms of supported functionality (it does inflections of words for fuzzy matching), and what you need to enable to use it (runs an extra windows service).