在 LINQ to SQL 中执行查询

发布于 2025-01-06 13:49:12 字数 698 浏览 2 评论 0原文

如何使用 LINQ to SQL 执行查询？询问事情是这样的。

假设我有这张表

CREATE TABLE dbo.Students
(
  StudentID INT IDENTITY(1,1) PRIMARY KEY,
  Name SYSNAME
);

CREATE TABLE dbo.StudentLoans
(
  LoanID INT IDENTITY(1,1) PRIMARY KEY,
  StudentID INT FOREIGN KEY REFERENCES dbo.Students(StudentID),
  Amount BIGINT -- just being funny
);

然后我想执行这个查询。

DECLARE 
  @Name       SYSNAME = N'user962206', 
  @LoanAmount BIGINT = 50000,
  @StudentID  INT;

INSERT dbo.Students(Name) 
  SELECT @Name;

SELECT @StudentID = SCOPE_IDENTITY();

INSERT dbo.StudentLoans(StudentID, Amount)
  SELECT @StudentID, @LoanAmount;

这可能吗？即使您的行和列已映射？如何使用 LINQ to SQL 执行该查询？

原文

How do I execute a query using LINQ to SQL? a query that something goes like this.

Let's say I have this table

CREATE TABLE dbo.Students
(
  StudentID INT IDENTITY(1,1) PRIMARY KEY,
  Name SYSNAME
);

CREATE TABLE dbo.StudentLoans
(
  LoanID INT IDENTITY(1,1) PRIMARY KEY,
  StudentID INT FOREIGN KEY REFERENCES dbo.Students(StudentID),
  Amount BIGINT -- just being funny
);

Then I wanted to execute this query.

DECLARE 
  @Name       SYSNAME = N'user962206', 
  @LoanAmount BIGINT = 50000,
  @StudentID  INT;

INSERT dbo.Students(Name) 
  SELECT @Name;

SELECT @StudentID = SCOPE_IDENTITY();

INSERT dbo.StudentLoans(StudentID, Amount)
  SELECT @StudentID, @LoanAmount;

Is that possible? even if your Rows and Columns are mapped? how can I execute that query with LINQ to SQL ?

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剩余の解释 2025-01-13 13:49:12

已经有一段时间了，但不会是这样的吧？

假设您已将所有表拖到 Linq2Sql 设计器上，只需创建一个 Student 对象，将 StudentLoan 添加到其 StudentLoans 集合，然后添加使用 myContextInstance.Students.InsertOnSubmit(newStudent) 将 Student 添加到 Context.Students 集合中，并且通过调用 myContextInstance.SubmitChanges 写出更改。

因此，将它们放在一起：

using(var myContextInstance=new YourContext())
{
    var student = new Student(){Name = "user962206"};
    var studentLoan = new StudentLoan(){Amount = 50000};
    student.StudentLoans.Add(studentLoan);
    myContextInstance.Students.InsertOnSubmit(student);
    myContextInstance.SubmitChanges();
}

如果您的 DataContext 如下所示，则代码片段有效：

在此处输入图像描述

这就是结果只需将表拖到 dbml 文件的设计界面即可。

It's been a while, but wouldn't it be something like this?

Assuming you've dragged all your tables onto the Linq2Sql designer, simply create a Student object, add a StudentLoan to its StudentLoans collection, and add the Student to the Context.Students collection with myContextInstance.Students.InsertOnSubmit(newStudent) and write out the changes with a call to myContextInstance.SubmitChanges.

So, putting it all together:

using(var myContextInstance=new YourContext())
{
    var student = new Student(){Name = "user962206"};
    var studentLoan = new StudentLoan(){Amount = 50000};
    student.StudentLoans.Add(studentLoan);
    myContextInstance.Students.InsertOnSubmit(student);
    myContextInstance.SubmitChanges();
}

The code snippet works if your DataContext looks like this:

enter image description here

This is the result of just dragging your tables to the design surface of the dbml file.

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