Question

我正在寻找一种使用'lookup'表来获取颜色值的方法。请参阅以下两个表中的示例并查找结果。

表格列和值：

ColumnName |   Condition       | CellColor
Rank       |   > 90            | Green
Rank       | between 70 and 89 | Yellow
Rank       |   < 70            | Red
Score      |   > 89            | Purple
Score      |   < 88            | Orange

人员表

Name | Rank | Score
Jane | 100  | 50
John | 77   | 90
Kelly| 50   | 99

我想要的结果

PersonnelName | Rank | RankCellColor | Score | Scoredcolor
Jane          | 100  |    Green      |  50   |  Orange
John          | 77   |   Yellow      |  90   |  Purple
Kelly         | 50   |    Red        |  99   | Purple

我试图遍历列排名和分数，但却陷入了如何使用条件的困境。我迷失了编码。我真的需要帮助来解决这个问题。

任何帮助都将不胜感激!!

Answer 1

SQL不适合此类问题。您可以将条件表结构为：

ColumnName, Lower, Upper, CellColor
Rank, 90, NULL, Green
Rank, 70,  89, Yellow
Rank, NULL, 70, Red
Score, 89, NULL, Purple
Score, NULL, 88, Orange

然后您的查询将如下所示：

select p.*, cr.color as rankcolor, cs.color as scorecolor
from personnel p left join
     conditions c
     on cr.columnname = 'Rank' and
        (p.rank >= cr.lower or cr.lower is null) and
        (p.rank <= cr.upper or cr.upper is null) left join
     conditions cs
     on cs.columnname = 'Score' and
        (p.score >= cs.lower or cs.lower is null) and
        (p.score <= cs.upper or cs.upper is null);

Answer 2

如果指定颜色的下限和上限，这将更容易。您可以加入值，其值在下限和上限范围内。

CREATE TABLE Conditions (ColumnName varchar(50), minval int, maxval int, CellColor varchar(50))
INSERT INTO Conditions
VALUES
 ('Rank', 90, 100, 'Green')
,('Rank', 70, 89, 'Yellow')
,('Rank', 0, 70, 'Red')
,('Score', 89, 100, 'Purple')
,('Score', 0, 88, 'Orange')

CREATE TABLE Personnel (Name varchar(50), Rank int, Score int)

INSERT INTO Personnel 
VALUES
 ('Jane', 100, 50)
,('John', 77, 90)
,('Kelly', 50, 99)

SELECT P.Name, P.Rank, ConRank.CellColor, P.Score, ConScore.CellColor
  FROM Personnel P 
       INNER JOIN Conditions ConRank 
        ON P.Rank >= ConRank.minval AND P.Rank <= ConRank.maxval AND ConRank.ColumnName = 'Rank'
       INNER JOIN Conditions ConScore
        ON P.Score >= ConScore.minval AND P.Score <= ConScore.maxval AND ConScore.ColumnName = 'Score'
ORDER BY P.Name

提供输出：

Name    Rank    CellColor   Score   CellColor
Jane    100     Green       50      Orange
John    77      Yellow      90      Purple
Kelly   50      Red         99      Purple

引用此sqlfiddle：http://sqlfiddle.com/#!6/15f3a/6

带有条件列的SQL查找表

2 个答案: