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_89 ( missing VARCHAR, unit VARCHAR, killed VARCHAR, wounded VARCHAR )

### Question ###
How many of the Royal Waggon Train Unit were Missing while having a Killed of 0 off 0 men and a Wounded of 0 off 0 men?

### Accurate SQL ###

SELECT missing FROM table_name_89 WHERE killed = "0 off 0 men" AND wounded = "0 off 0 men" AND unit = "royal waggon train"