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  1. Practice
  2. SQL
  3. Basic Select
  4. Weather Observation Station 5
  5. Discussions

Weather Observation Station 5

  • deepshashank + 3 comments

    SIR CAN YOU EXPLAIN THIS PLEASE

    • dhananjayt771 + 2 comments

      SET @V1 := (SELECT MIN(LENGTH(CITY)) FROM STATION); SET @V2 := (SELECT CITY FROM STATION WHERE LENGTH(CITY) = @V1 ORDER BY CITY LIMIT 1);

      SET @V3 := (SELECT MAX(LENGTH(CITY)) FROM STATION); SET @V4 := (SELECT CITY FROM STATION WHERE LENGTH(CITY) = @V3 ORDER BY CITY LIMIT 1);

      SELECT @V2,@V1; SELECT @V4,@V3;

      • return1 + 0 comments

        PLease explain this

      • saurabh250987si1 + 0 comments

        Thanks dhananjay.. it worked :-)

    • dwayneuni + 0 comments

      I second it. Can you please explain this.

    • pedrokarneiro + 0 comments

      Hello Deep...

      This query is about unifying the results of two subqueries, so we use the UNION clause.

      The WHERE ROWNUM = 1 in both subqueries is there in order to do a "TOP 1". That is the way this is done in Oracle. It is not very didactic but that's how Oracle undestands it. A simple explanation for that is here: https://stackoverflow.com/questions/3451534/how-do-i-do-top-1-in-oracle

      The reason of what I have put in the ORDER BY, I think it is due to the statement of the challenge, but I'd have to look into it again.

      All the best!