CREATE TABLE table_45276 ("Senator" TEXT, "Party" TEXT, "District" FLOAT, "Home Town" TEXT, "Took Office" FLOAT)

What district has a democratic leader from Roby?
SELECT SUM("District") FROM table_45276 WHERE "Party" = 'democratic' AND "Home Town" = 'roby'
SELECT SUM("District") FROM "table_45276" WHERE "Home Town" = 'roby' AND "Party" = 'democratic'