CREATE TABLE "table1_12148018_2" (
  "num" real,
  "episode" text,
  "director" text,
  "writer" text,
  "original_airdate" text,
  "viewers" text
);

Question:  who is the writer where viewers is 5.16m
SQL: SELECT "writer" FROM "table1_12148018_2" WHERE "viewers"='5.16m';

Question:  who is the writer for episode "episode 7"
SQL: SELECT "writer" FROM "table1_12148018_2" WHERE "episode"='\"Episode 7\"';