Yes, editing the data connection SQL command permanently changes the default query. However, the query command is available to be updated at any time using code before you query.
When using LIKE, you need to use the "%"s. The LIKE clause *is* your wildcard...
So if you use:
SELECT * FROM table WHERE column LIKE '%an%'
This will select any row where 'column' has the string "an" in it. This is not case-sensitive. Note the use of the single quote character around the "%"s.
"*" by itself is not a wild card in SQL. But using LIKE with % give you that.