Table: senate_successors
Columns: state_class
vacator
reason_for_change
successor
date_of_successors_formal_installation

Question: What change caused a change of staff in March 9, 1865?
SQL: SELECT "reason_for_change" FROM senate_successors WHERE "date_of_successors_formal_installation" = 'March 9, 1865'

Question: Who was the successor for the new seat?
SQL: SELECT "successor" FROM senate_successors WHERE "vacator" = 'New seat'

Question: What was the reason for change in staff in formal installations on March 15, 1865?
SQL: SELECT "reason_for_change" FROM senate_successors WHERE "date_of_successors_formal_installation" = 'March 15, 1865'

Question: Who was the successor for the new seat?
SQL: SELECT "successor" FROM senate_successors WHERE "vacator" = 'New seat'