Question

    CUSTOMER(CustID, CustName)
    Sale(SaleNo, StockNo, CustNo, SaleDate)

如何删除自2009年以来未购买任何商品的客户？

我可以使用减号

来获取CustID

    SELECT CustID FROM CUSTOMER
    WHERE SaleDate <= to_date('31-12-09', 'DD-MM-YY')
    MINUS
    SELECT CustID FROM CUSTOMER
    WHERE SaleDate > to_date('31-12-09', 'DD-MM-YY');

但我不知道如何在单个查询中执行删除。

任何建议都将受到赞赏

Answer 1

delete from CUSTOMER c
inner join Sale S 
on C.CustID=S.CustNo
where max(SaleDate)<='31-12-09'

Answer 2

^{您没有指定您的DBMS，虽然我怀疑它是Oracle，因为使用了MINUS和to_date()}

无论如何，以下内容应适用于Oracle（以及任何符合ANSI标准的DBMS）

delete from customer
where not exists (select 1 
                  from sale
                  where sale.custId = customer.CustNo
                    and sale.saledate >= date '2009-01-01')

Answer 3

在SQL Server中

DELETE FROM Customer
WHERE CustID IN ( SELECT CustNo FROM Sale 
                  GROUP BY CustNo
                  HAVING YEAR(MAX(SaleDate))<2009)

在MySQL中

DELETE FROM Customer
WHERE CustID IN ( SELECT CustNo FROM Sale 
                  GROUP BY CustNo
                  HAVING EXTRACT(YEAR FROM MAX(SaleDate))<2009)

SQL DELETE使用DATE

3 个答案: