SQL Server存储过程中的datetime参数选择数据

Question

I have a football league database and I am trying to get the current score of the teams on a specific date. If I type in a date in the past I want the score at that specific date - the points of each teams on that date.

In my database I have a table that includes all the matches and I have a table with the teams and their point (this table is actually the same as the current score).

The two tables are:

 create table teams
 (
 id char(3) primary key,
 name varchar(40),
 nomatches int,
 owngoals int,
 othergoals int,
 points int
 )

 create table matches
 (
 id int identity(1,1),
 homeid char(3) foreign key references teams(id),
 outid char(3) foreign key references teams(id),
 homegoal int,
 outgoal int,
 matchdate datetime
 )

I am trying to use a stored procedure where I have a datetime as a parameter to show the current score (the team table) at that date defined by the parameter.

Right now I'm selecting all the matches that is bigger (newer) than the date I want til score table from and subtracting the result of that match from the teams point.

But it seems to me that it is a lot of work to do for something that simple.

Does anyone have a better idea?

Answer 1

Why do you subtract? Seems to me that the correct way to go would be to take the league start date and calculate the scores from that day up to selected date.

Answer 2

I'm not sure why you would want to put such a simple query into a procedure, but essentially what you're asking is as follows:

CREATE PROCEDURE sp_goals_to_date(@todate DATETIME) AS    
    SELECT id, SUM(homegoal) AS homegoal, SUM(outgoal) AS outgoal FROM matches WHERE matchdate <= @mydate

What Fedor says is correct - it is more efficient to do a single calculation from the beginning of time, than to have to do a calc from two different tables.

Answer 3

I would first transform the matches table like this:

SELECT
  teamid    = CASE t.calchometeam WHEN 1 THEN m.homeid   ELSE m.outid   END,
  owngoal   = CASE t.calchometeam WHEN 1 THEN m.homegoal ELSE m.outgoal END,
  othergoal = CASE t.calchometeam WHEN 0 THEN m.homegoal ELSE m.outgoal END,
  points    = CASE m.homegoal
    WHEN m.outgoal THEN @drawpoints
    ELSE (SIGN(m.homegoal - m.outgoal) + 1) / 2 ^ ~m.playedhome) * @winpoints
       + (SIGN(m.homegoal - m.outgoal) + 1) / 2 ^ m.playedhome) * @losspoints
  END
FROM matches m
CROSS JOIN (
  SELECT CAST(0 AS bit) UNION ALL
  SELECT CAST(1 AS bit)
) AS t (calchometeam)
WHERE m.matchdate <= @givendate

Now it's easier to calculate the necessary totals:

SELECT
  teamid,
  nomatches  = COUNT(*),
  owngoals   = SUM(owngoal),
  othergoals = SUM(othergoal),
  points     = SUM(points)
FROM transformed_matches
GROUP BY
  teamid

Next step would be to join the last result set to the teams table to get the team's names. And if you actually need that final step, you could, of course, perform the calculations the way you intended from the beginning, ie calculate only the stats you need to subtract from the current values, rather than the actual standings. So, using this inverted logic, the entire query might look like this:

WITH
transformed_matches AS (
  SELECT
    matchid   = m.id,
    teamid    = CASE t.calchometeam WHEN 1 THEN m.homeid   ELSE m.outid   END,
    owngoal   = CASE t.calchometeam WHEN 1 THEN m.homegoal ELSE m.outgoal END,
    othergoal = CASE t.calchometeam WHEN 0 THEN m.homegoal ELSE m.outgoal END,
    points    = CASE m.homegoal
      WHEN m.outgoal THEN @drawpoints
      ELSE (SIGN(m.homegoal - m.outgoal) + 1) / 2 ^ ~m.playedhome) * @winpoints
         + (SIGN(m.homegoal - m.outgoal) + 1) / 2 ^ m.playedhome) * @losspoints
    END
  FROM matches m
  CROSS JOIN (
    SELECT CAST(0 AS bit) UNION ALL
    SELECT CAST(1 AS bit)
  ) AS t (calchometeam)
  WHERE m.matchdate > @givendate
),
aggregated AS (
  SELECT
    teamid,
    nomatches  = COUNT(*),
    owngoals   = SUM(owngoal),
    othergoals = SUM(othergoal),
    points     = SUM(points)
  FROM transformed_matches
  GROUP BY
    teamid
)
SELECT
  t.id,
  t.name,
  nomatches  = t.nomatches  - ISNULL(a.nomatches , 0),
  owngoals   = t.owngoals   - ISNULL(a.orngoals  , 0),
  othergoals = t.nomatches  - ISNULL(a.othergoals, 0),
  points     = t.points     - ISNULL(a.points    , 0)
FROM teams t
  LEFT JOIN aggregated a ON t.id = a.teamid

Note: You didn't specify which kind of football you meant, but living in Europe, it was easier for me to assume association football rather than any other kind. Yet, because I was not sure, I decided to parametrise my query. That is why you can see all those @winpoints , @drawpoints and @losspoints placeholders. You can replace the variables with the actual constants, if you like, or you could leave the query parametrised in case you wanted to satisfy your curiosity as to what the team's standings would have been if a different scoring system were in effect.