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_10592536_8 ( date_of_vacancy VARCHAR, team VARCHAR, replaced_by VARCHAR )

### Question ###
What is the date of vacancy when the team is manchester city and replaced by is mark hughes?

### Accurate SQL ###

SELECT date_of_vacancy FROM table_10592536_8 WHERE team = "Manchester City" AND replaced_by = "Mark Hughes"