Strange Issue while using underscore and hyphen in SQL Server

Question

Strangely when I compare '-' (hyphen) with a '_' (underscore) , I'm getting weird results. Although I expect the output of both the below statements to be false , the first one returns true while the second one returns false.

1. Select case when '-' like '_' then 'true' else 'false' end -- returns true
2. Select case when '_' like '-' then 'true' else 'false' end -- returns false

Any clarification would be helpful.

Answer 1

the underscore (_) and the percent(%) are wildcards when used in SQL LIKE clause

if you want these characters to be interpreted not as wildcards, you must escape them, like this

http://www.sqldbpros.com/2013/01/escaping-from-an-underscore-in-a-sql-server-wildcard-like-search/