CREATE TABLE table_30891 ("Number" CLOB, "Serial Number" FLOAT, "Into Service" CLOB, "Withdrawn" CLOB, "Scrapped" CLOB)

Name the into service for dh2
SELECT "Into Service" FROM table_30891 WHERE "Number" = 'DH2'
SELECT "Into Service" FROM "table_30891" WHERE "Number" = 'DH2'