user: Question: Who was the deceased spouse who was married for 4 years?
Columns: ['Name', 'Deceased Spouse', 'Cause of Death', 'Date of Spouses Death', 'Length of Marriage', 'Children Together', 'Current Marital Status']
Types: ['text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Chester A. Arthur', 'Ellen Lewis Herndon Arthur', 'Pneumonia', 'January 12, 1880 (aged42)', '21 years', '1 Daughter (Ellen) 2 Sons (William, Chester II)', 'Deceased (1886)']
SQL:

assistant: SELECT "Deceased Spouse" FROM "Table" WHERE "Length of Marriage" = '4 years';