Question

我有两个名为

的表

式：

===================
   id  |  style
===================
    1  |  x
===================
    2  |  y

尺寸：

===========================================
   id  |  size_name  | style_id  | Quantity
===========================================
    1  |  2T         |  1        |  200
===========================================
    2  |  3T         |  1        |  100
===========================================
    3  |  4T         |  2        |  250
===========================================
    4  |  2T         |  2        |  500

使用这两个表我想要一个如下的报告：

=============================================
  Style  |              size                      
=============================================
         |    2T   |    3T    |    4T    |    
=============================================
   x     |    200  |    100   |    0     |
=============================================
   y     |    500  |     0    |   250    |

提前致谢。请帮忙

Answer 1

静态查询（如果已知且数量有限的size_name）

SELECT st.Style
  ,SUM(CASE WHEN s.size_name = '2T' THEN Quantity ELSE 0 END) AS `2T`
  ,SUM(CASE WHEN s.size_name = '3T' THEN Quantity ELSE 0 END) AS `3T`
  ,SUM(CASE WHEN s.size_name = '4T' THEN Quantity ELSE 0 END) AS `4T`
FROM Size s
JOIN Style st ON s.style_id = st.id
GROUP BY st.Style;

动态查询（如果您不知道size_name的数量）

SET @sql = NULL;
SELECT
  GROUP_CONCAT(DISTINCT
    CONCAT(
      'SUM(CASE WHEN `size_name` = ''',
      `size_name`,
      ''' THEN Quantity ELSE 0 END) AS `',
      `size_name`, '`'
    )
  ) INTO @sql
FROM Size;

SET @sql = CONCAT('SELECT st.Style , ', @sql, '
                  FROM Size s
                  JOIN Style st ON s.style_id = st.id
                   GROUP BY st.Style 
                  ');

PREPARE stmt FROM @sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;

输出：

╔══════╦═════╦═════╦═════╗
║ TYLE ║ 2T  ║ 3T  ║ 4T  ║
╠══════╬═════╬═════╬═════╣
║ x    ║ 200 ║ 100 ║   0 ║
║ y    ║ 500 ║   0 ║ 250 ║
╚══════╩═════╩═════╩═════╝

请参阅this SQLFiddle

Answer 2

试试这个

  select 
  style , 
  max(case when size_name = '2T' then Quantity else 0 end) as '2T' ,
  max(case when size_name = '3T' then Quantity else 0 end) as '3T' ,
  max(case when size_name = '4T' then Quantity else 0 end) as '4T'
  from style inner join size
  on size.style_id = style.id
  group by style.id

demo here

在自定义视图中显示记录

2 个答案:

请参阅this SQLFiddle