CREATE TABLE table_58983 ("Outcome" TEXT, "Date" TEXT, "Championship" TEXT, "Surface" TEXT, "Opponent in the final" TEXT, "Score in the final" TEXT)

What Championship has a Date of 26 may 1986?
SELECT "Championship" FROM table_58983 WHERE "Date" = '26 may 1986'
SELECT "Championship" FROM "table_58983" WHERE "Date" = '26 may 1986'