使用实体框架和本机 sql 从 vb.net 中的 sqlserver 检索数据
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Retrieve data from sqlserver in vb.net using entity framework and native sql
提问by Khushi
I want to retrieve data in Winforms using vb.net, entity framework and native sql. I have used the code below which allows me to add data to the sql:
我想使用 vb.net、实体框架和本机 sql 在 Winforms 中检索数据。我使用了下面的代码，它允许我向 sql 添加数据：
Private Sub frmMain_Load(sender As Object, e As EventArgs) Handles MyBase.Load
Dim db As New SampleDBEntities
Dim bs As New BindingSource
bs.DataSource = db.Cars.Local
DataGridView1.DataSource = bs
End Sub
But I don't know how to fire a query to retrieve data from database. Suppose I want to get all the records from Cars table in my Database named SampleDB.
So I need "SELECT * FROM Cars",
but how to use this query?
但我不知道如何触发查询以从数据库中检索数据。假设我想从名为 SampleDB 的数据库中的 Cars 表中获取所有记录。所以我需要"SELECT * FROM Cars"，但如何使用这个查询？
采纳答案by Recipe
Either you work with SQL directly (through SQL or stored procedures) and communicate with the server using SqlConnection, SqlCommand and perhaps DataReader or DataAdapter or you correctly use the Entity Framework that you have configured.
要么直接使用 SQL（通过 SQL 或存储过程）并使用 SqlConnection、SqlCommand 和 DataReader 或 DataAdapter 与服务器通信，要么正确使用已配置的实体框架。
I'm not really into VB.Net, so it'll be pseudocode, but you need to be addressing your EF context.
我不是真的到 VB.Net，所以它会是伪代码，但你需要解决你的 EF 上下文。
Something like
就像是
using (myEntityModel context = new myEntityModel())
{
MyResult = context.Cars.where(c => c.model == "myModel").ToList();
}
回答by OneFineDay
To get all the cars it would be:
要获得所有汽车，它将是：
Using db As New SampleDBEntities
Dim cars = db.Cars.ToList
End Using
To get all cars by type, if you have a 'type' field in that entity.
要按类型获取所有汽车，如果该实体中有“类型”字段。
Using db As New SampleDBEntities
Dim mazdaCars = db.Cars.Where(Function(c) c.Type = "Mazda").ToList
End Using
ENtity Framework was built for LINQ and Lambda. Be sure to close/dispose your entity container object.
实体框架是为 LINQ 和 Lambda 构建的。请务必关闭/处置您的实体容器对象。
