Question

我要删除select语句中存在特定列的行，例如：

delete from [ProjectCustomer] pcc 
where ProjectKey in (
  select p.ProjectKey  
  FROM [Project] AS [p] inner JOIN [ProjectDesign] AS [pd] ON [p].[ProjectKey] = [pd].[ProjectKey]
  inner JOIN [Design] AS [d] ON [pd].[DesignKey] = [d].[DesignKey]
  inner JOIN [ProjectCustomer] AS [pc] ON [pc].[ProjectKey] = [p].[ProjectKey]
  inner join Customer as c on pc.CustomerKey = c.CustomerKey
  where d.Folio = 3014)

但是在delete语句的where子句中我得到

where子句附近的语法不正确

我在做什么错？问候

Answer 1

具有表别名的DELETE语句具有不同的语法，因此您可以删除别名而不使用它，或者更改删除语句，例如@Martin注释。

delete pcc from [ProjectCustomer] pcc

我愿意使用INNER JOIN而不是IN来修改查询

delete pcc from [ProjectCustomer] AS pcc 
  inner join [Project] AS [p] ON [p].ProjectKey = [pcc].ProjectKey
  inner JOIN [ProjectDesign] AS [pd] ON [p].[ProjectKey] = [pd].[ProjectKey]
  inner JOIN [Design] AS [d] ON [pd].[DesignKey] = [d].[DesignKey]
  inner JOIN [ProjectCustomer] AS [pc] ON [pc].[ProjectKey] = [p].[ProjectKey]
  inner join Customer as c on pc.CustomerKey = c.CustomerKey
  where d.Folio = 3014)

Answer 2

我认为错误消息是

“ pcc”附近的语法不正确

代替

where子句附近的语法不正确

您将收到第一条错误消息，因为您使用的别名错误，因此当您不加入目标表时，您可能会想要

delete from [ProjectCustomer]
where ProjectKey in (
  select p.ProjectKey  
  FROM [Project] AS [p] inner JOIN [ProjectDesign] AS [pd] ON [p].[ProjectKey] = [pd].[ProjectKey]
  inner JOIN [Design] AS [d] ON [pd].[DesignKey] = [d].[DesignKey]
  inner JOIN [ProjectCustomer] AS [pc] ON [pc].[ProjectKey] = [p].[ProjectKey]
  inner join Customer as c on pc.CustomerKey = c.CustomerKey
  where d.Folio = 3014);

，或者即使您仍想使用别名

delete pcc from [ProjectCustomer] pcc
where pcc.ProjectKey in ...

Answer 3

您可以稍微简化查询。我认为您不需要子查询，可以在第一个FROM子句中指定要删除的表（不带别名），然后在第二个表中联接表（随便使用别名）：

DELETE FROM ProjectCustomer
FROM ProjectCustomer pc
  INNER JOIN ProjectDesign pd ON pc.ProjectKey = pd.ProjectKey
    INNER JOIN Design d ON pd.DesignKey = d.DesignKey
WHERE d.Folio = 3014;

Customers和Products表不是必需的，只要您设置了参照完整性并且pc.CustomerKey不可为空。

删除选择语句中存在列的行

3 个答案: