请用SQL语句完成下列SQL操作。表如下COUNTRIES(CountryName, DocName, DocPhone) COMPETITORS(SporterID, Name, BirthDay, CountryName) EVENTS(SportName, CompName, LocationID, Date, Time) ...... 5. 列出同一赛次中分获第一、第二名的同一国家队的队友，所列信息含国家名、第一名运动员号及名字，第二名运动员号及名字6. 列出参加所有竞赛项目的国家，使用关联子查询

5.

SELECT c.CountryName, e1.SporterID AS FirstPlaceID, e1.Name AS FirstPlaceName, e2.SporterID AS SecondPlaceID, e2.Name AS SecondPlaceName
FROM COUNTRIES c
JOIN COMPETITORS c1 ON c.CountryName = c1.CountryName
JOIN EVENTS e1 ON c1.SporterID = e1.SporterID
JOIN EVENTS e2 ON e1.SportName = e2.SportName AND e1.LocationID = e2.LocationID AND e1.Date = e2.Date AND e1.Time = e2.Time AND e1.SporterID <> e2.SporterID
WHERE e1.SporterID IN (SELECT MIN(SporterID) FROM EVENTS WHERE SportName = e1.SportName AND LocationID = e1.LocationID AND Date = e1.Date AND Time = e1.Time)
AND e2.SporterID IN (SELECT MIN(SporterID) FROM EVENTS WHERE SportName = e2.SportName AND LocationID = e2.LocationID AND Date = e2.Date AND Time = e2.Time)

6.

SELECT DISTINCT c.CountryName
FROM COUNTRIES c
WHERE NOT EXISTS (
    SELECT e.SportName
    FROM EVENTS e
    WHERE NOT EXISTS (
        SELECT cp.SporterID
        FROM COMPETITORS cp
        WHERE cp.CountryName = c.CountryName AND cp.SporterID = e.SporterID
    )
)