SQL Server advanced sorting out - sql

Question

I am an asp.net web pages developer I am developing a website in which I need advanced sorting like www.olx.com which is a classifieds website but the problem is that I have more than 25 categories I am using SQL Server & have my tables broken into parts.
Now, as I have many categories so when i sort them for example if I search for samsung but at the same time I want to sort search data by price (high to low or low to high) & also at same time I want to filter data which has a description now I would need to make 100's of queries by using if's but is there a more convenient solution to this problem
Currently I am using this query:
sql = "SELECT * FROM users_table INNER JOIN response_table ON users_table.ID = response_table.ID LEFT OUTER JOIN miscellaneous_table ON users_table.ID = miscellaneous_table.ID LEFT OUTER JOIN response_table2 ON users_table.ID = response_table2.ID";
sql = sql + " where response_table.sub_category='" + incat + "'";
if (Request["search"] != "" && Request["search"] != null)
{
var search = Request["search"].Trim();
string[] querynew = search.Split(' ');
var searchquery = " and ";
foreach (string word in querynew)
{
searchquery += " users_table.adtitle LIKE '%" + word + "%' OR ";
}
sql = sql + searchquery.Remove(searchquery.Length - 4);
}
if (Request["min"] != "" && Request["min"] != null && Request["max"] != null && Request["max"] != "")
{
sql = sql + " and (CAST(response_table.price AS Float)) between " + Request["min"].Trim() + " AND " + Request["max"].Trim();
}
Thanks

Answer 1

You can use this short hand in the WHERE clause
Assuming your filter are #col1, #col2, #col3
SELECT ...
FROM ...
WHERE (#col1 = 0 OR col1 = #col1)
AND (#col2 = '' OR col2 = #col2)
AND (#col3 = 0 OR col3 = #col3)
So with the above where clause, if the user only supply filter for col2 then just pass 0 in for col1 & col2 and it will unfilter these.