表结构
public class User
{
[Key]
public int UserId { set; ...
public class User
{
[Key]
public int UserId { set; get; }
[StringLength(8)]
[Required]
public string Name { set; get; }
public int Age { get; set; }
}
给User的name字段添加索引
public class DBContext : DbContext
{
public DbSetUsers { set; get; }
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity().HasIndex(b => b.Name).IsUnique(); ;
}
......
}
using (var db = new DBContext())
{
db.Database.EnsureCreated();
Random r1 = new Random();
var user = new User { Name = "bing_" + r1.Next(100).ToString() };
db.Users.Add(user);
return db.SaveChanges().ToString();
}
public string Del(int id)
{
using (var db = new DBContext())
{
var user = new User { UserId = id };
db.Users.Remove(user);
return db.SaveChanges().ToString();
}
}
public string Update(int id)
{
using (var db = new DBContext())
{
//var user = new User
//{
// UserId = id,
// Name = "bomo",
// Age = 29,
//};
////更新全部字段
//db.Users.Update(user);
//更新部分字段
db.Users.Single(u => u.UserId == id).Name = "test";
return db.SaveChanges().ToString();
}
}
public string Select(int id)
{
using (var db = new DBContext())
{
//根据id查询
//var user = db.Users.Single(u => u.UserId == id);
//根据name过滤查询
var user = db.Users
.Where(u => u.Name.Contains("test"))
.First();
return user.Name;
}
}
public ListSelect(int id)
{
using (var db = new DBContext())
{
var user = db.Users
.Where(u => EF.Functions.Like(u.Name,"bing%"))
.ToList();
return user;
}
}
以上只是简单的实现增删改查,详细使用方法可以查看官网文档https://docs.microsoft.com/en-
us/ef/core/querying/basic
如果这篇文章对你有所帮助,可以通过下边的“打赏”功能进行小额的打赏。
本网站部分内容来源于互联网,如有侵犯版权请来信告知,我们将立即处理。