Where the built as is DLG-23, what is the class?
CREATE TABLE "references" (
  "ship" text,
  "built_as" text,
  "reclassified_as" text,
  "class" text,
  "commissioned_decommissioned" text,
  "nvr_link" text
);
SELECT "class" FROM "references" WHERE "built_as"='dlg-23';