SQL Wildcards using %%%

Question

I'm wondering what problems I may not foresee by using this query:

SELECT * 
FROM tanswer 
WHERE CourseID LIKE '%%%' AND Q39 LIKE 'p' AND Q42 LIKE 'a' AND Q43 LIKE 'a'

In particular using '%%%'.

The reason being, I have a dropdown that would send a '%' and in the sql I enclose it with the other two % to search through a set of courses, this query leaving the courseID searching through all courses.

The recordset returned seems to work fine, but I'm not sure if there's anything I may not be seeing by using three %%% together. Is this a special use of wildcards that I've stumbled across?

Answer 1

These are equivalent:

 CourseID LIKE '%%%'
 CourseID LIKE '%%'
 CourseID LIKE '%'

Which is why your query behaves as you expected it to.

Answer 2

You need to use ! to escape the inner % : ie %!%%

see here