Question

我想从1列中获取值，然后将它们转换为另一列的标题。它更容易告诉你：

初始表：

Name      | Label   | Value
Tom Jones | January | 42
Rick James| March   | 83

结束表：

Name      | January | March
Tom Jones | 42      | NULL
Rick James| NULL    | 83

由于我在Label上进行的排序和排序类型，因此需要这样的格式。

更新：当我提到多列值时，我的意思是：

Name      | Label_1   | ValueA_1 | ValueB_1 | Label_2 | ValueA_2 | ValueB_2
Tom Jones | January   | 42       | 77       | March   | 99       | 22
Rick James| March     | 83       | 17       | May     | NULL     | 112

Answer 1

使用CREATE TABLE NewTable AS SELECT ...：

CREATE TABLE newTable
SELECT
  NAme, 
  SUM(CASE WHEN Label = 'January' THEN value  END) AS January,
  SUM(CASE WHEN Label = 'March' THEN value END) AS March
FROM tablename AS t1
GROUP BY Name;

这将创建一个全新的表newTable，其结构与SELECT语句相同。

<强>更新

根据您的评论，如果您想获得value逗号分隔的值：

CREATE TABLE newTable
SELECT
  Name, 
  GROUP_CONCAT(CASE WHEN Label = 'January' THEN value  END) AS January,
  GROUP_CONCAT(CASE WHEN Label = 'March' THEN value  END) AS March
FROM table1 AS t1
GROUP BY Name;

SQL Fiddle Demo

更新

如果你想动态地执行此操作，而不是硬编码值，则必须使用动态sql来执行此操作，如下所示：

SET @sql = NULL;

SELECT
  GROUP_CONCAT(DISTINCT CONCAT('GROUP_CONCAT(IF(Label = ''',
      Label, ''', value, NULL)) AS ', '''', Label , '''')
  ) INTO @sql
FROM Table1 ;

SET @sql = CONCAT('CREATE TABLE newTable ',
                  'SELECT Name,' ,
                  @sql, ' FROM table1 ',
                  ' GROUP BY Name');


prepare stmt 
FROM @sql;

execute stmt;

SQL创建列从值并填充其他列

1 个答案:

更新

Updated SQL Fiddle Demo