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_51977 ( "Nat." text, "Name" text, "Moving to" text, "Type" text, "Transfer window" text, "Transfer fee" text )

### Question ###
What is the transfer window with n/a as the Transfer fee, free agent for the Moving to, and Joe Sagar as the name?

### Accurate SQL ###

SELECT "Transfer window" FROM table_51977 WHERE "Transfer fee" = 'n/a' AND "Moving to" = 'free agent' AND "Name" = 'joe sagar'