SQL查询两个表

Question

I am having problems with queries:
My tables are following:

Drivers

|DRIVER_ID|FIRST_NAME|LAST_NAME|AGE|
|        1|John      |Smith    |19 |
|        2|Steve     |Oak      |33 |
|        3|Mary      |Sanchez  |22 |

Drivers_in_Teams

|DRIVERS_IN_TEAMS_ID|DRIVER_ID|TEAM_ID|BEG_DATE |END_DATE |
|                  1|        1|      1|18-NOV-05|    -    |
|                  2|        3|      2|10-APR-12|    -    |
|                  3|        2|      3|19-JUL-01|02-AUG-04|

BEG_DATEs are done with "sysdate-number"

I would like to make one query, where it displays the oldest driver with first and last name, who is still in a team.

I tried some examples which I have found from google, but I can't get them to work. I'm beginner in SQL and I have no idea how to do this query.

an example I found

SELECT FIRST_NAME, LAST_NAME 
FROM DRIVER, DRIVERS_IN_TEAMS 
WHERE DRIVER.DRIVER_ID = DRIVERS_IN_TEAMS.DRIVER_ID 
AND DRIVERS_IN_TEAMS.BEG_DATE =  
     SELECT (SELECT MIN(BEG_DATE) 
             FROM DRIVERS_IN_TEAMS) (SELECT MAX(AGE) 
     FROM DRIVERS);

Answer 1

Try this:

select top 1 first_name, last_name from Drivers as d
    inner join Drivers_in_Teams as dit on d.driver_id = dit.driver_id
where isnull(end_date,'')=''
order by age desc

Comment if you have any questions or code doesn't work.

Answer 2

I think it should work. No resources to test and debug. Let me know if there are any problems.

SELECT first_name FROM driver WHERE
driver_id in (select unique(driver_id) from driver_in_teams where end_date is NULL) 
and age =(select MAX(age) from drivers)

Alternative:

SELECT first_name FROM driver d
INNER JOIN
driver_in_teams dt ON (d.driver_id=dt.driver_id)
WHERE dt.END_DATE IS NULL
AND d.age=(select MAX(age) from drivers)

Answer 3

SELECT FIRST_NAME, LAST_NAME, AGE 
FROM Drivers
JOIN Drivers_in_Teams ON Drivers.DRIVER_ID = Drivers_in_Teams.DRIVER_ID
WHERE Drivers_in_Teams.END_DATE IS NULL
ORDER BY AGE DESC

This should join the two tables with the DRIVER_ID on each, and then display only records that are NULL , which I would assume is the '-' in your END_DATE field.

Answer 4

This should do the trick:

-- get the data you want
SELECT first_name, last_name, age FROM drivers d
 WHERE d.age = (
    -- get the max age from drivers still actives
    SELECT MAX(age) FROM driver WHERE driver_id IN (
    -- get drivers still active
        SELECT drive_id FROM drivers_in_teams WHERE end_date IS NULL
    ) x