CREATE TABLE table_5062 ("Race" CLOB, "Length" CLOB, "Class" CLOB, "Circuit" CLOB, "Date" CLOB)

Name the length for all class and date of march 18
SELECT "Length" FROM table_5062 WHERE "Class" = 'all' AND "Date" = 'march 18'
SELECT "Length" FROM "table_5062" WHERE "Class" = 'all' AND "Date" = 'march 18'