SQL在内部联接中的AS中选择

Question

我有这种查询，我想按类别选择，例如（'CENTRAL'，'EASTERN'）中的Region作为A1，选择（'NORTHERN'，'SOUTHERN'）中的Region作为A2

如何在我的查询中添加？

SELECT
  locinvaisle.Region AS Region,
  sum(sales_data.QUANTITY/1000) AS UnitMT
FROM
  sales_data
  INNER JOIN locinvaisle ON locinvaisle.Location = sales_data.LOCATION
WHERE
 sales_data.unit = 'KG'
 and
 sales_data.CUSTOMERACCOUNT not in ('CT1008','CT1009')
 group by locinvaisle.Region

Answer 1

我认为如果您的数据库是mysql ， oracle ， mssql等通用数据库，则可以使用IF或CASE ：

SELECT
  CASE WHEN locinvaisle.Region = 'CENTRAL' OR locinvaisle.Region = 'EASTERN' THEN 'A1'
  CASE WHEN locinvaisle.Region = 'NORTHERN' OR locinvaisle.Region = 'SOUTHERN' THEN 'A2'
  ELSE 'Default'
  END
    AS Region,
  sum(sales_data.QUANTITY/1000) AS UnitMT
FROM
  sales_data
  INNER JOIN locinvaisle ON locinvaisle.Location = sales_data.LOCATION
WHERE
 sales_data.unit = 'KG'
 and
 sales_data.CUSTOMERACCOUNT not in ('CT1008','CT1009')
 group by Region