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_1251 ( "No. in series" text, "No. Disc" real, "Title" text, "Directed by" text, "Written by" text, "Original air date" text, "Length (minutes)" real )

### Question ###
Name the maximum number of disc for bill gereghty

### Accurate SQL ###

SELECT MAX("No. Disc") FROM table_1251 WHERE "Directed by" = 'Bill Gereghty'