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_681 ( "District" text, "Incumbent" text, "Party" text, "First elected" real, "Results" text, "Candidates" text )

### Question ###
When was the incumbent Sherrod Brown first elected?

### Accurate SQL ###

SELECT MAX("First elected") FROM table_681 WHERE "Incumbent" = 'Sherrod Brown'