Question

如何编写LINQ to SQL等效于：

INSERT INTO Table1 (field1, field2, field3)
SELECT field1, field2, field3
FROM Table2
WHERE (field1= @field1)

由于

Answer 1

由于您没有返回任何结果，只需使用低级DataContext.ExecuteCommand()方法：

using (MyDataContext dc = new MyDataContext())
{
    dc.ExecuteCommand(@"
        INSERT INTO Table1 (field1, field2, field3)
        SELECT field1, field2, field3
        FROM Table2
        WHERE (field1= {0})
        ",
        field1);
}

Answer 2

LINQ是一种查询语言，因此它不会进行更新或插入。但是，LINQ to SQL实体对象模型具有处理CUD的方法：

using(MyDataContext dc = new MyDataContext())
{
    //select the source entities from Table2
    var Table2Entities = (from e in dc.Table2 where e.Field1 == "value" select e);

    //for each result, create a new Table1 entity and attach to Table1
    Table2Entities.ForEach(t2e => dc.Table1.InsertOnSubmit(
        new Table1Entity {
            Field1 = t2e.Field1,
            Field2 = t2e.Field2,
            Field3 = t2e.Field3
        });

    //submit the changes
    dc.SubmitChanges();
}

这里的真正区别在于它需要两个单独的SQL事务而不是一个 - 一个用于选择，一个用于插入。

Answer 3

如果两个表的字段相同，那么，使用

insert into table1 select * from table2 where table2.field1='xyz';

取代：

INSERT INTO Table1 (field1, field2, field3)
SELECT field1, field2, field3
FROM Table2
WHERE (field1= @field1)

如何在LINQ中“INSERT INTO table1（...）SELECT（...）FROM table2”？

3 个答案: