根据出现次数将包含状态的列添加到 table

Question

我的 SQL table 包含两列：订单和订单行。现在我想在我的 table 中添加第三列（状态）以指示它是单行订单还是多行订单。如果订单号只出现一次，则 'Single line' 否则 'Multi line'。我怎样才能做到这一点？谢谢！

Order	Order Line	Status
10000	10	Single line
10001	10	Multi line
10001	20	Multi line
10002	10	Single line

Answer 1

使用 window functions (Also called Analytics Functions 或有序分析函数):

SELECT Order, 
  OrderLine, 
  CASE WHEN COUNT(OrderLine) OVER (PARTITION BY Order) > 1 THEN 'Mult line' ELSE 'Single line' END as Status
FROM yourtable;

根据出现次数将包含状态的列添加到 table

Add column containing status to table based on number of occurrences

sql

sql-server