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 school (school_id VARCHAR, school_name VARCHAR)
TABLE: CREATE TABLE endowment (donator_name VARCHAR, school_id VARCHAR)

### Question ###
How many donors have endowment for school named "Glenn"?

### Accurate SQL ###

SELECT COUNT(DISTINCT T1.donator_name) FROM endowment AS T1 JOIN school AS T2 ON T1.school_id = T2.school_id WHERE T2.school_name = "Glenn"