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_name_22 ( post VARCHAR, trainer VARCHAR, time__behind VARCHAR )

### Question ###
What is the total number of Post, when Trainer is 'Steve Asmussen', and when Time/ Behind is 19 ?

### Accurate SQL ###

SELECT COUNT(post) FROM table_name_22 WHERE trainer = "steve asmussen" AND time__behind = "19 ½"