CREATE TABLE "membership" (
  "school" text,
  "location" text,
  "mascot" text,
  "county" text,
  "year_joined" real,
  "previous_conference" text,
  "year_left" real,
  "conference_joined" text
);

Question: Which Conference Joined has a Previous Conference of northwestern, and a Mascot of oilers?
SQL: SELECT "conference_joined" FROM "membership" WHERE "previous_conference"='northwestern' AND "mascot"='oilers';

Question: Which Year Left is the highest one that has a Location of east chicago, and a Year Joined of 1969, and a School of east chicago roosevelt?
SQL: SELECT MAX("year_left") FROM "membership" WHERE "location"='east chicago' AND "year_joined"=1969 AND "school"='east chicago roosevelt';

Question: Which Year Left is the lowest one that has a School of calumet, and a Year Joined larger than 1993?
SQL: SELECT MIN("year_left") FROM "membership" WHERE "school"='calumet' AND "year_joined">1993;