Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_19089486_1 (clubs_involved INTEGER, leagues_entering_this_round VARCHAR, round VARCHAR)

### Question ###
Name the least clubs involved for leagues being none for semi finals

### Accurate SQL ###

SELECT MIN(clubs_involved) FROM table_19089486_1 WHERE leagues_entering_this_round = "none" AND round = "Semi finals"