main方法调用连接
using System;
using MySql.Data.MySqlClient;
class Program
{
static void Main(string[] args)
{
string connectionString = "server=localhost;database=***;username=***;password=****";
using (MySqlConnection connection = new MySqlConnection(connectionString))
{
//try
//{
// connection.Open();
// // 执行数据库操作
// Console.WriteLine("连接成功!");
//}
//catch (MySqlException ex)
//{
// Console.WriteLine("数据库连接失败: " + ex.Message);
//}
try
{
connection.Open();
string query = "SELECT * FROM aaa";
MySqlCommand cmd = new MySqlCommand(query, connection);
MySqlDataReader reader = cmd.ExecuteReader();
while (reader.Read())
{
Console.WriteLine(reader["SHORI_NEN"].ToString());
}
reader.Close();
}
catch (Exception ex)
{
Console.WriteLine(ex.ToString());
}
connection.Close();
}
}
}
上面是练习 下面是api重点哦
1.Program.cs 文件添加
添加对配置文件的引用
//builder.Configuration.AddJsonFile("appsettings.json", optional: false, reloadOnChange: true);
配置连接字符串
//var connectionString = builder.Configuration.GetConnectionString("DefaultConnection");
添加数据库上下文服务
//builder.Services.AddDbContext<StudentContext>(options =>
// options.UseMySql(connectionString, ServerVersion.AutoDetect(connectionString))
//);
或者
builder.Services.AddDbContext<StudentContext>(options =>
options.UseMySql(builder.Configuration.GetConnectionString("DefaultConnection"), new MySqlServerVersion(new Version())));
主要是引入json文件
2.appsettings.json
"ConnectionStrings": {
"DefaultConnection": "server=localhost;database=****;username=*****;password=******"
},
Program里的"DefaultConnection"要和json一致哦
这时候就已经配置好连接了
3.新建Moudels 文件夹
创建学生Student
namespace TodoApi.Models
{
public class Student
{
[Key]
public int Id { get; set; }
//大小写都可以 带下划线的需要和数据库一致 也可以配置（自己百度）
public string Name { get; set; } = String.Empty;
public string Age { get; set; } = String.Empty;
}
}
数据库记得建表
CREATE TABLE `student` (
`Id` int NOT NULL COMMENT 'OID',
`Name` varchar(2) NOT NULL COMMENT '名称',
`Age` varchar(1) NOT NULL COMMENT '年龄'
)
4.创建StudentContext文件
using Microsoft.EntityFrameworkCore;
using WebApplication777.Models;
namespace TodoApi.Models
{
public class StudentContext : DbContext
{
public StudentContext(DbContextOptions<StudentContext> options) : base(options)
{
}
public DbSet<Student> Students { get; set; }
public DbSet<MsgMst> MsgMsts { get; set; }
//OnModelCreating ToTable为了映射数据库
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
//entity（自己的表） ToTable （填写数据库的名字）
modelBuilder.Entity<Student>().ToTable("student");
modelBuilder.Entity<MsgMst>().ToTable("msg_mst");
}
}
}
5.controller
建立StudentController
using Microsoft.AspNetCore.Mvc;
using TodoApi.Models;
using WebApplication777.Models;
namespace TodoApi.Controllers
{
[Route("api/[controller]")]
[ApiController]
public class StudentController : ControllerBase
{
private readonly StudentContext _context;
public StudentController(StudentContext context)
{
_context = context;
}
[HttpGet("{id}")]
public async Task<ActionResult<Student>> Get(int id)
{
var studentsId = await _context.Students.FindAsync(id);
if (studentsId == null)
{
return NotFound();
}
return studentsId;
}
}
}
这时候就可以查询数据库啦
记得点赞哈
第一次学c#