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_261931_2 (institution VARCHAR, nickname VARCHAR)

### Question ###
Which institution's nickname is the Polar Bears?

### Accurate SQL ###

SELECT institution FROM table_261931_2 WHERE nickname = "Polar Bears"