CREATE TABLE "singles_28" (
  "edition" text,
  "round" text,
  "date" text,
  "against" text,
  "surface" text,
  "opponent" text,
  "result" text
);

Question: On which date was the opponent lamine ouahab?
SQL: SELECT "date" FROM "singles_28" WHERE "opponent"='lamine ouahab';

Question: On what date did the match take place in a round of 1r and have a result 2–6, 5–7, 2–6?
SQL: SELECT "date" FROM "singles_28" WHERE "round"='1r' AND "result"='2–6, 5–7, 2–6';

Question: What is the result of the match in round 1r against tunisia and on a hard surface?
SQL: SELECT "result" FROM "singles_28" WHERE "round"='1r' AND "surface"='hard' AND "against"='tunisia';

Question: Who was the match against when on a clay surface during round 2r?
SQL: SELECT "against" FROM "singles_28" WHERE "round"='2r' AND "surface"='clay';

Question: What round had a amtch against cyprus and an edition of 2010 davis cup europe/africa group ii?
SQL: SELECT "round" FROM "singles_28" WHERE "edition"='2010 davis cup europe/africa group ii' AND "against"='cyprus';