用 if....then 更新 table

Question

我的数据库中有这个 table：

GroupStandings
+--------+----------+--------------+--------+
| TeamID | GoalsFor | GoalsAgainst | Points |
+--------+----------+--------------+--------+
|      1 |        0 |            0 |      0 |
|      2 |        0 |            0 |      0 |
|      3 |        0 |            0 |      0 |
|      4 |        0 |            0 |      0 |
+--------+----------+--------------+--------+

我想编写一个查询，根据我将 GoalsFor 和 GoalsAgainst 更新为什么来更新点。澄清一个非常糟糕的例子：

update GroupStandings
set GoalsFor = 3, GoalsAgainst = 1,
    if GoalsFor>GoalsAgainst set points = 3
    else if GoalsFor=GoalsAgainst set points =1
    else set points = 0
where TeamID = 1

Answer 1

不确定您的示例查询的工作版本是否是您想要实现的全部，但如果是这样您想要使用 CASE:

update GroupStandings
set GoalsFor = 3
  , GoalsAgainst = 1
  , points = CASE WHEN GoalsFor>GoalsAgainst THEN 3
                  WHEN GoalsFor=GoalsAgainst THEN 1
                  ELSE 0
             END
where TeamID = 1

更新：

基于所有值为 0 的开始，您可以将 Points 设为计算列：

ALTER TABLE YourTable DROP COLUMN Points;
GO
ALTER TABLE YourTable ADD Points AS (CASE WHEN GoalsFor>GoalsAgainst THEN 3
                                          WHEN GoalsFor=GoalsAgainst THEN 1
                                          ELSE 0
                                    END);

或者您可以运行 2 次更新：

update GroupStandings
set GoalsFor = 3
  , GoalsAgainst = 1
where TeamID = 1
GO
update GroupStandings
set points = CASE WHEN GoalsFor>GoalsAgainst THEN 3
                  WHEN GoalsFor=GoalsAgainst THEN 1
                  ELSE 0
             END
where TeamID = 1

或者您可以使用变量来存储您的更新值并在单个更新中使用它们：

DECLARE @GoalsFor INT = 3
       ,@GoalsAgainst INT = 1
update GroupStandings
set GoalsFor = @GoalsFor
  , GoalsAgainst = @GoalsAgainst
  , points = CASE WHEN @GoalsFor>@GoalsAgainst THEN 3
                  WHEN @GoalsFor=@GoalsAgainst THEN 1
                  ELSE 0
             END
where TeamID = 1

Answer 2

检查此代码，希望对您有所帮助：

在此代码中，您可以在变量中设置 GoalsFor 和 GoalsAgainst 值，然后进行比较以针对每个 teamid 更新分数。

Declare @GoalsFor int 
Declare @GoalsAgainst int

Set @GoalsFor = 3
Set @GoalsAgainst = 1 

Update GroupStandings Set GoalsFor = @GoalsFor, GoalsAgainst = @GoalsAgainst, 
Points = Case When @GoalsFor > @GoalsAgainst then 3 
              When @GoalsFor = @GoalsAgainst then 1 
              else 0 end
Where TeamId = 1

select * from GroupStandings

用 if....then 更新 table

update table with if....then

sql

sql-server

sql-server-2012