本文所介紹的是真正的EF+CodeFirst，不需要提前建表，由代碼自動生成！
進行前需要准備的：
1、下載Sqlite Expert
http://www.sqliteexpert.com/download.html
2、下載后新建數據庫，然后保存到你指定的目錄即可（保存為.db文件）
不需要新建表
然后在VS中->工具->擴展和更新->聯機
搜索SQLite/SQL Server Compact ToolBox ，下載完后重啟VS###
(這個插件安裝后，在選擇數據源時已經可以選擇SQLite了，但是保存的時候會提示失敗，還需要安裝另一個插件)
在同一個地方再搜索dotConnect ADO.NET Data Provider for SQLite，記得不是安裝Standard的，點下載后會出現個彈出框下載，下載完后安裝時要先關閉VS
3然后開始敲重點了
1） 先在NuGet中添加相關依賴項：Entity Framework，SQLite、System.Data.SQLite、System.Data.SQLite.EF6和SQLite.CodeFirst；
(始終復制至本地)
2）添加命名空間
using System.Data.Entity;
using SQLite.CodeFirst;
3. 定義實體類(數據類型需要和數據庫保持一致，否則報錯)
public class UsersInfo
{
public int Id { get; set; } = 1;
public string Name { get; set; } = "2";
public string Password { get; set; } = "1";
public int RoleId { get; set; } = 0;
}
4. Model配置類
class UserConfig: EntityTypeConfiguration<UsersInfo>
{
public UserConfig()
{
this.ToTable("T_Users");
}
}
添加Context類，繼承自DbContext
public class MyDbContext:DbContext
{
public MyDbContext():base("name=SQLiteConnect")
{
}
public DbSet<UsersInfo> User { get; set; }
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
base.OnModelCreating(modelBuilder);
Assembly ass = Assembly.GetExecutingAssembly();
modelBuilder.Configurations.AddFromAssembly(ass);
}
}
5. 獲取數據庫連接字符串
工具->連接到數據庫->更改->選擇SQLite Database->Browse數據庫文件->測試成功后復制Connection String
5. 修改配置文件APP.config
5.1 在</system.data>結點后面添加連接字符串（其中相對路徑可以"Data Source=.\SQLLiteTest.db" ）
<connectionStrings>
<add name="SQLiteConnect" connectionString="Data Source=F:\xxx\SQLLiteTest.db" providerName="System.Data.SQLite.EF6"/>
</connectionStrings>
5.2 添加Provider結點（主要原因是SQLite的invarianName不是在自動生成的.EF6里面）
<provider invariantName="System.Data.SQLite" type="System.Data.SQLite.EF6.SQLiteProviderServices, System.Data.SQLite.EF6" />
<provider invariantName="System.Data.SQLite.EF6" type="System.Data.SQLite.EF6.SQLiteProviderServices, System.Data.SQLite.EF6" />
如不進行provider注冊，后續操作會出現以下錯誤
6. 新建窗體測試
6.1 界面窗口布局
6.2 按鈕事件
private void btnAdd_Click(object sender, EventArgs e)
{
List<Student> books = new List<Student>()
{
new Student() {ID=1, Name = "小明", Age = 11, Gender = "男" },
new Student() {ID=2, Name = "老王", Age = 12, Gender = "男" },
new Student() {ID=3, Name = "小郭", Age = 10, Gender = "女" },
new Student() {ID=4, Name = "小李", Age = 11, Gender = "男" },
new Student() {ID=5, Name = "小玉", Age = 9, Gender = "女" },
};
using (var db = new StudentContext())
{
db.Students.AddRange(books);
int count = db.SaveChanges();
this.Text = $"{DateTime.Now}, 插入{count}條記錄";
}
}
private void btnModify_Click(object sender, EventArgs e)
{
using (var db = new StudentContext())
{
var students = db.Students.FirstOrDefault(x => x.Name == "小李");
if (students != null)
{
students.Age += 1;
int count = db.SaveChanges();
this.Text = $"{DateTime.Now}, 修改{count}條記錄";
}
}
}
private void btnDel_Click(object sender, EventArgs e)
{
using (var db = new StudentContext())
{
var students = db.Students.FirstOrDefault(x => x.Name == "小玉");
if (students != null)
{
var result = db.Students.Remove(students);
int count = db.SaveChanges();
this.Text = $"{DateTime.Now}, 刪除{count}條記錄";
}
}
}
private void btnQuery_Click(object sender, EventArgs e)
{
using (var db = new StudentContext())
{
var students = db.Students.Where(x => x.Name == "老王").OrderByDescending(x => x.Age).ToList();
this.Text = $"{DateTime.Now}, 查到{students.Count}條記錄";
this.dataGridView1.DataSource = students;
}
}
private void btnRefresh_Click(object sender, EventArgs e)
{
using (var db = new StudentContext())
{
var students = db.Students.ToList();
this.dataGridView1.DataSource = students;
}
}
7. 效果
根據代碼生成表（表中主鍵注意要設置為自增，否則報錯）
