EF Core中执行Sql语句查询操作之FromSql,ExecuteSqlCommand,SqlQuery

 

一、目前EF Core的版本为V2.1

相比较EF Core v1.0 目前已经增加了不少功能。

EF Core除了常用的增删改模型操作,Sql语句在不少项目中是不能避免的。

在EF Core中上下文,可以返货DbConnection ,执行sql语句。这是最底层的操作方式,代码写起来还是挺多的。

初次之外 EF Core中还支持 FromSql,ExecuteSqlCommand 连个方法,用于更方便的执行Sql语句。

另外,目前版本的EF Core 不支持SqlQuery,但是我们可以自己扩展一个。坐等升级以后支持吧。

1.FromSql,执行列表查询

public static IQueryable<TEntity> FromSql<TEntity>([NotNullAttribute] this IQueryable<TEntity> source, 
[NotParameterized] RawSqlString sql,
[NotNullAttribute] params object[] parameters) where TEntity : class;

这种方式,仅用于当前上线文中注册的 模型对象。

对于上下文DbSet<T>中没有定义的不起作用。

示例代码1:

EF Core中执行Sql语句查询操作之FromSql,ExecuteSqlCommand,SqlQuery
    //执行sql查询语句 FromSql()
    QLLB_SWXContext _Context = new QLLB_SWXContext();
    string sql = "select * from Article where CategoryID=1;";
    List<Article> list = _Context.Article.FromSql(sql).ToList();
    foreach (var item in list)
    {
        Console.WriteLine(item.Title);
    }
EF Core中执行Sql语句查询操作之FromSql,ExecuteSqlCommand,SqlQuery

示例代码2:视图中的查询

EF Core中执行Sql语句查询操作之FromSql,ExecuteSqlCommand,SqlQuery
---创建视图,查询没有分配角色的菜单
create view view_NoRole
as 
select * from Sys_Navigation
where NavID not in (
select distinct  NavID   from Sys_Role_Nav 
)
EF Core中执行Sql语句查询操作之FromSql,ExecuteSqlCommand,SqlQuery
EF Core中执行Sql语句查询操作之FromSql,ExecuteSqlCommand,SqlQuery
//查询视图
    string sql2 = "select * from view_NoRole";
    List<SysNavigation> roleList = _Context.SysNavigation.FromSql(sql2).ToList();
    foreach (var item in roleList)
    {
        Console.WriteLine(item.Title);
    }
EF Core中执行Sql语句查询操作之FromSql,ExecuteSqlCommand,SqlQuery

2.ExecuteSqlCommand,执行Sql操作处理

QLLB_SWXContext _Context = new QLLB_SWXContext();
//执行数据操作sql,返回受影响的行数
string sql = "update Sys_Role set SortValue=1 ;";
int count = _Context.Database.ExecuteSqlCommand(sql);
Console.WriteLine(count);

3.自定义SqlQuery,执行列表查询,在上线文中不存的对象。

示例代码1:

EF Core中执行Sql语句查询操作之FromSql,ExecuteSqlCommand,SqlQuery
QLLB_SWXContext _Context = new QLLB_SWXContext();
//特别说明,自定义分装的不支持 单个值查询
//不支持object 查询
//自定义查询操作 SqlQuery
string sql = "select sum(ViewCount)*1.11 as allCount from Article;";
TempData result = _Context.Database.SqlQuery<TempData>(sql).FirstOrDefault();
Console.WriteLine(result.AllCount);
EF Core中执行Sql语句查询操作之FromSql,ExecuteSqlCommand,SqlQuery

对象定义

EF Core中执行Sql语句查询操作之FromSql,ExecuteSqlCommand,SqlQuery
public class TempData
{
    public int CategoryID { get; set; }
    public string Title { get; set; }
    public int ArtCount { get; set; }
    /// <summary>
    /// 求和结果
    /// </summary>
    public decimal AllCount { get; set; }
}
EF Core中执行Sql语句查询操作之FromSql,ExecuteSqlCommand,SqlQuery

示例代码2:

执行视图查询:

EF Core中执行Sql语句查询操作之FromSql,ExecuteSqlCommand,SqlQuery
--定义视图,文章分类和对应分类的文章数量
create view view_CateCount
as
select C.CategoryID,C.Title,  (
select count(*) from Article where CategoryID=C.CategoryID
) as ArtCount  from ArticleCategory C;
EF Core中执行Sql语句查询操作之FromSql,ExecuteSqlCommand,SqlQuery

C#代码:

EF Core中执行Sql语句查询操作之FromSql,ExecuteSqlCommand,SqlQuery
//组合查询
string sql2 = "select * from view_CateCount;";
List<TempData> tempList = _Context.Database.SqlQuery<TempData>(sql2).ToList();
foreach (var item in tempList)
{
    Console.WriteLine(item.Title);
}
EF Core中执行Sql语句查询操作之FromSql,ExecuteSqlCommand,SqlQuery

SqlQuery扩展定义:

EF Core中执行Sql语句查询操作之FromSql,ExecuteSqlCommand,SqlQuery
EF Core中执行Sql语句查询操作之FromSql,ExecuteSqlCommand,SqlQuery
using Microsoft.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore.Infrastructure;
using System;
using System.Collections.Generic;
using System.Data;
using System.Data.Common;
using System.Data.SqlClient;
using System.Reflection;
using System.Text;

namespace QL.Card.Entity
{
    public static class DbContextExtensions
    {
        private static void CombineParams(ref DbCommand command, params object[] parameters)
        {
            if (parameters != null)
            {
                foreach (SqlParameter parameter in parameters)
                {
                    if (!parameter.ParameterName.Contains("@"))
                        parameter.ParameterName = $"@{parameter.ParameterName}";
                    command.Parameters.Add(parameter);
                }
            }
        }

        private static DbCommand CreateCommand(DatabaseFacade facade, string sql, out DbConnection dbConn, params object[] parameters)
        {
            DbConnection conn = facade.GetDbConnection();
            dbConn = conn;
            conn.Open();
            DbCommand cmd = conn.CreateCommand();
            if (facade.IsSqlServer())
            {
                cmd.CommandText = sql;
                CombineParams(ref cmd, parameters);
            }
            return cmd;
        }

        public static DataTable SqlQuery(this DatabaseFacade facade, string sql, params object[] parameters)
        {
            DbCommand cmd = CreateCommand(facade, sql, out DbConnection conn, parameters);
            DbDataReader reader = cmd.ExecuteReader();
            DataTable dt = new DataTable();
            dt.Load(reader);
            reader.Close();
            conn.Close();
            return dt;
        }

        public static IEnumerable<T> SqlQuery<T>(this DatabaseFacade facade, string sql, params object[] parameters) where T : class, new()
        {
            DataTable dt = SqlQuery(facade, sql, parameters);
            return dt.ToEnumerable<T>();
        }

        public static IEnumerable<T> ToEnumerable<T>(this DataTable dt) where T : class, new()
        {
            PropertyInfo[] propertyInfos = typeof(T).GetProperties();
            T[] ts = new T[dt.Rows.Count];
            int i = 0;
            foreach (DataRow row in dt.Rows)
            {
                T t = new T();
                foreach (PropertyInfo p in propertyInfos)
                {
                    if (dt.Columns.IndexOf(p.Name) != -1 && row[p.Name] != DBNull.Value)
                        p.SetValue(t, row[p.Name], null);
                }
                ts[i] = t;
                i++;
            }
            return ts;
        }
    }
}
EF Core中执行Sql语句查询操作之FromSql,ExecuteSqlCommand,SqlQuery

 

 更多:

.NetCore中EFCore的使用整理

.NetCore中EFCore的使用整理(二)-关联表查询

 .NetCore中EFCore for MySql整理(三)之Pomelo.EntityFrameworkCore.MySql

 

EF Core中执行Sql语句查询操作之FromSql,ExecuteSqlCommand,SqlQuery

(0)
(0)
   
举报
评论 一句话评论(0
上一篇:Prometheus+Grafana可视化监控MySQL


下一篇:MYSQL8.0安装配置