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_15 ( school VARCHAR, year_joined VARCHAR, year_left VARCHAR )

### Question ###
Which school joined in 1971 and left in 1975?

### Accurate SQL ###

SELECT school FROM table_name_15 WHERE year_joined = "1971" AND year_left = "1975"