Question

我想从表中删除一些数据。我想删除内部联接中未包含的数据

到目前为止我的查询：

 DELETE *how do you say delete what wasn't included in the inner join?*
 from dbo.Cloudpie c
 inner join dbo.cake p
 on c.cakeid = p.cakeid
where cakeid > 1

提前感谢您提供的所有帮助：）！

Answer 1

您可以使用LEFT OUTER JOIN：

DELETE c
FROM dbo.Cloudpie c
LEFT OUTER JOIN dbo.cake p
    ON c.cakeid = p.cakeid
WHERE p.cakeid IS NULL AND c.cakeid > 1

使用NOT EXISTS

甚至更简单，更不容易出错（在可空列上）：

DELETE c
FROM dbo.Cloudpie c
WHERE NOT EXISTS( SELECT 1 FROM dbo.cake p
                  WHERE p.cakeid = c.cakeid ) 
AND c.cakeid > 1

值得一读：http://www.sqlperformance.com/2012/12/t-sql-queries/left-anti-semi-join

使用内部联接删除

1 个答案: