mysql - 如何使一条记录的值成为mysql上字段的标题？

Question

这个问题已经有答案了:

SQL Transpose Rows as Columns (5 个回答)

已关闭 4 年前。

我的查询是这样的:

SELECT a.number, a.description, b.attribute_code, b.attribute_value 
FROM items a 
JOIN attr_maps b ON b.number = a.number WHERE a.number = AB123

如果执行查询，结果如下:

我想要这样的结果:

我该怎么做？

Answer 1

您可以使用条件聚合:

SELECT i.number, i.description,
       MAX(CASE WHEN am.attribute_code = 'brand' then am.attribute_value END) as brand,
       MAX(CASE WHEN am.attribute_code = 'model' then am.attribute_value END) as model,
       MAX(CASE WHEN am.attribute_code = 'category' then am.attribute_value END) as category,
       MAX(CASE WHEN am.attribute_code = 'subcategory' then am.attribute_value END) as subcategory
FROM items i JOIN
     attr_maps am
     ON am.number = i.number
WHERE i.number = AB123
GROUP BY i.number, i.description