mysql - 从行数据添加列名称

Question

我有一张 table

stock   idWarehouse  Warehousname  idorder
-492    1               xyz          1
-24     3               abc          1
-492    1               xyz          2 
-24     3               abc          2

我想要以下形式的结果

xyz  abc    idorder
-492  -24     1
-492  -24     2

Answer 1

如果 Warehousename 的值集有限，您可以执行以下操作:

SELECT MAX(CASE WHEN Warehousname='xyz' THEN stock END) AS xyz,
       MAX(CASE WHEN Warehousname='abc' THEN stock END) AS abc,
       idorder
FROM TableName
GROUP BY idorder

结果示例:

xyz     abc     idorder
-492    -24     1
-492    -24     2

SQL Fiddle 中的示例结果.