having子句在sql中不起作用

Question

我不明白这个陈述中的错误。

  Select customername,LEN(address) 
  FROM customers group by customername having LEN(address) = 13;

这是错误消息 HAVING子句（LEN（地址）= 13）没有分组或聚合。

Answer 1

address中LEN(address)和GROUP BY都不在。{1}}。因此，您需要添加它们或将表达式包装在聚合函数中：

SELECT customername, MAX(LEN(address))
FROM customers 
GROUP BY customername 
HAVING MAX(LEN(address)) = 13;

或者，如果您只想要长度为13的客户，则可能根本不需要聚合：

SELECT customername
FROM customers 
WHERE LEN(address) = 13;

Answer 2

尝试使用where子句

  Select customername,LEN(address) as lenadressnamecolumn
  FROM customers where LEN(address) = 13;