CREATE TABLE table_11190568_7 (date_of_vacancy VARCHAR2, replaced_by VARCHAR2)

When is the date of vacancy of Davy Fitzgerald being a replacement?
SELECT date_of_vacancy FROM table_11190568_7 WHERE replaced_by = "Davy FitzGerald"
SELECT "date_of_vacancy" FROM "table_11190568_7" WHERE "Davy FitzGerald" = "replaced_by"