SQL

Question

来自不同id的table需要合并成一行

        +-----+-----+-----+-----+
        | Id  | Col1| Col2| Col3|
        +-----+-----+-----+-----+
        | 1   |     |   1 |     |
        | 2   |     |   2 |     |
        | 3   |   3 |     |     |
        | 4   |   4 |     |     |
        | 5   |     |     |   5 |
        | 6   |     |     |   6 |
        +-----+-----+-----+-----+

我想在同一个 table 中实现什么。

        +-----+-----+-----+-----+
        | Id  | Col1| Col2| Col3|
        +-----+-----+-----+-----+
        | 1   |   3 |   1 |   5 |
        | 2   |   4 |   2 |   6 |
        +-----+-----+-----+-----+

我曾尝试使用不同的 id 聚合行

Select ID
      ,ID1 = max(Col1)
      ,ID2 = max(Col2)
      ,ID3 = max(Col3)
 From  Tbl
 Group By ID

Answer 1

我不知道你想从这个结果中得到什么，但你可以尝试这样的查询：

Select ID
      ,(select max(Col1) from tbl) as ID1
      ,(select max(Col2) from tbl) as ID2
      ,(select max(Col3) from tbl) as ID3
 From  Tbl
 Group By ID

Answer 2

您的数据

create table test(
   Id   INTEGER  NOT NULL 
  ,Col1 INTEGER  
  ,Col2 INTEGER
  ,Col3 INTEGER
);
INSERT INTO test
(Id,Col1,Col2,Col3)
VALUES
(1,NULL,1,NULL),
(2,NULL,2,NULL),
(3,3,NULL,NULL),
(4,4,NULL,NULL),
(5,NULL,NULL,5),
(6,NULL,NULL,6);

UNION Max 函数与 Min 函数的结果

SELECT 1         AS ID,
       Min(col1) Col1,
       Min(col2) Col2,
       Min(col3) Col3
FROM   test
UNION
SELECT 2         AS ID,
       Max(col1) Col1,
       Max(col2) Col2,
       Max(col3) Col3
FROM   test

另外你可以使用multiple join和Subbquery和Where条件来

SELECT a.id1 AS id,
       b.col1,
       a.col2,
       c.col3
FROM  (SELECT Row_number()
                OVER (
                  ORDER BY id ) id1,
              *
       FROM   Test
       WHERE  col2 IS NOT NULL) a
      JOIN (SELECT Row_number()
                     OVER (
                       ORDER BY id ) id1,
                   *
            FROM   Test
            WHERE  col1 IS NOT NULL) b
        ON a.id1 = b.id1
      JOIN(SELECT Row_number()
                    OVER (
                      ORDER BY id ) id1,
                  *
           FROM   Test
           WHERE  col3 IS NOT NULL) c
        ON a.id1 = c.id1

dbfiddle

SQL - 将不同的行合并为具有不同 ID 的单行

SQL - Combine different rows into a single row with different ID

sql-server