Question

我继承了一个可怕设计的表，其中数据存储如下：

Period |  Identifier |   Value
----------------------------------
1      | AB1         | some number
1      | AB2         | some number
1      | AB3         | some number
1      | AB4         | some number
1      | AB5         | some number
1      | A1          | some number
1      | A2          | some number
1      | A3          | some number
1      | A4          | some number
1      | A5          | some number
2      | AB1         | some number
2      | AB2         | some number
2      | AB3         | some number
2      | AB4         | some number
2      | AB5         | some number
2      | A1          | some number
2      | A2          | some number
2      | A3          | some number
2      | A4          | some number
2      | A5          | some number

我正在尝试使用SELECT语句将数据转换为这种格式：

Row # | First value | Second value
1     | A1's number | AB1's number     // The next 5 rows are data from period 1
2     | A2's number | AB2's number
3     | A3's number | AB3's number
4     | A4's number | AB4's number
5     | A5's number | AB5's number
6     | A1's number | AB1's number     // These 5 rows are from period 2
7     | A2's number | AB2's number
8     | A3's number | AB3's number
9     | A4's number | AB4's number
10    | A5's number | AB5's number

AB%和A%是该格式的两个独立ID，我认为这会轻微挫败WHERE LIKE ...条款。我不完全确定数据可以强制进入所需的格式，但我的主管让我调查一下。

我最初的尝试，我不知道SQL代码，将是查看行号本身并使用，但正如我所说，我不确定如何沿着这条路线前进。

目前，数据位于SQL Server中，但可以使用proc sql从SAS访问。我认为这些标准大部分都符合SQL Server，即使不支持DECLARE。

不，我不知道以这种方式存储数据的想法是什么......

Answer 1

如果标识符中的“B”仅用于区分A类和AB类标识符，那么您只需删除该字母并加入结果：

SELECT ROW_NUMBER() OVER(ORDER BY AData.Period, AData.[Identifier]) AS [Row #]
    , AData.[Identifier] AS [First Value]
    , ABData.[Identifier] AS [Second Value]
FROM YourTable AData
-- Change to a LEFT JOIN if not all A's have AB's.
JOIN YourTable ABData
    -- NOTE: Assumes that 'B' is the only differentiator between
    -- AData and ABData's Identifier column and that it is
    -- not repeated as part of the common identifier.
    ON AData.[Identifier] = REPLACE(ABData.[Identifier], 'B', '')

你是完全正确的 - 它不是一个非常棒的架构 - 这可能需要全表扫描。

Answer 2

如果您使用SAS，那么我只使用PROC TRANSPOSE。获取数据以包含标签变量，该变量确定将数据移动到哪个变量：

data datatable;
infile datalines dlm='|';
input
Period Identifier $ Value $;
datalines;
1      | AB1         | some number
1      | AB2         | some number
1      | AB3         | some number
1      | AB4         | some number
1      | AB5         | some number
1      | A1          | some number
1      | A2          | some number
1      | A3          | some number
1      | A4          | some number
1      | A5          | some number
2      | AB1         | some number
2      | AB2         | some number
2      | AB3         | some number
2      | AB4         | some number
2      | AB5         | some number
2      | A1          | some number
2      | A2          | some number
2      | A3          | some number
2      | A4          | some number
2      | A5          | some number
;;;
run;

data have;
set datatable;
idlabel = compress(identifier, ,'d');
byval = compress(identifier,,'kd');
run;

proc sort data=have;
by period byval;
run;
proc transpose data=have out=want;
by period byval;
id idlabel;
var value;
run;

如果由于某种原因你必须在SQL中执行它，那么最好将它作为自身的连接。你想加入期间= 1的行，并且对AB和A都压缩（标识符，'kd'）= 1，所以你可以这样做：

proc sql;
  create table want as 
    select A.period, AB.value as AB, A.value as A
    from (select * from have where compress(identifier,,'d')='AB') AB, 
         (select * from have where compress(identifier,,'d')='A') A
    where AB.period=A.period
    and compress(AB.identifier,,'kd') = compress(A.identifier,,'kd');
quit;

但PROC TRANSPOSE选项可能比自联接更有效率，我认为（如果您的数据不如您所显示的那么漂亮，则更灵活）。

Answer 3

忽略在特定时段内将A与AB关联一秒的棘手问题，如果数据能够以某种方式相关，我会通过在表上对其自身进行内部连接来选择您要查找的格式，从而：

SELECT row_number() OVER(ORDER BY a.Period, a.Identifier, b.Identifier), 
       a.Value, 
       b.Value 
FROM TableName a 
  INNER JOIN TableName b ON join_mechanism 
ORDER BY a.Period, a.Identifier, b.Identifier

现在，要填写连接机制，显而易见的部分是a.Period = b.Period。可疑部分是一个想法，如果此文本是静态的，您可以尝试替换字符串。所以REPLACE（a.Identifier，'A'，'AB'）= b。标识符。

因此，总而言之，你会有：

SELECT row_number() OVER(ORDER BY a.Period, a.Identifier, b.Identifier), 
       a.Value, 
       b.Value 
FROM TableName a 
  INNER JOIN TableName b ON a.Period = b.Period AND REPLACE(a.Identifier, 'A', 'AB') = b.Identifier 
ORDER BY a.Period, a.Identifier, b.Identifier

注意：SELECT语句尚未经过测试，我假设您使用的是支持row_number的相对较新版本的MSSQL。

我如何使用SELECT语句将这些数据从两列转换为三列？

3 个答案: