Table: dh_rolling_stock
Columns: number
serial_number
into_service
withdrawn
scrapped

Question: Name the into service for dh1
SQL: SELECT "into_service" FROM dh_rolling_stock WHERE "number" = 'DH1'

Question: Name the withdrawn for example and serial number 579
SQL: SELECT "withdrawn" FROM dh_rolling_stock WHERE "into_service" = 'Example' AND "serial_number" = 579

Question: Name the into service for dh2
SQL: SELECT "into_service" FROM dh_rolling_stock WHERE "number" = 'DH2'

Question: Name the most serial number for feb 1994
SQL: SELECT MAX("serial_number") FROM dh_rolling_stock WHERE "scrapped" = 'Feb 1994'

Question: Name the number for 2004 scapped
SQL: SELECT "number" FROM dh_rolling_stock WHERE "scrapped" = '2004'

Question: Name the into service for dh1
SQL: SELECT "into_service" FROM dh_rolling_stock WHERE "number" = 'DH1'