Entity Framework 基礎操做(1)

EF是微軟推出的官方ORM框架，默認防注入能夠配合LINQ一塊兒使用，更方便開發人員。

首先經過SQLSERVER如今有的數據庫類生產EF

右鍵-》添加-》新建項，選擇AOD.NET實體數據模型，來自數據庫的Code FIrst

完成添加後會生成多個文件，而且在你的項目的配置文件中有數據庫的連接字符串，下面文件中 「name=Test」,

Test就是鏈接字符串的name

public partial class TestDB : DbContext
{
    public TestDB()
        : base("name=Test")
    {
    }

    public virtual DbSet<School> School { get; set; }
    public virtual DbSet<Student> Student { get; set; }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
}

public partial class School
{
    [StringLength(50)]
    public string SchoolId { get; set; }

    [StringLength(50)]
    public string Name { get; set; }

    public DateTime? CreateTime { get; set; }

    [StringLength(100)]
    public string Address { get; set; }

    [StringLength(50)]
    public string Telephone { get; set; }
}

public partial class Student
{
    [StringLength(50)]
    public string StudentId { get; set; }

    [StringLength(50)]
    public string Name { get; set; }
}

School和Student就是根據數據庫表來生成的類

經過泛型來作基礎操做

class BaseDB<T> where T : class, new()
{
    DbContext Db = new Test();

    //查詢
    public IQueryable<T> LaodEntities(System.Linq.Expressions.Expression<Func<T, bool>> whereLambda)
    {
        return Db.Set<T>().Where<T>(whereLambda);
    }

    //更新
    public bool EditEntity(T entity)
    {
        Db.Entry<T>(entity).State = EntityState.Modified;
        return Db.SaveChanges() > 0;
    }

    //添加
    public bool AddEntity(T entity)
    {

        Db.Set<T>().Add(entity);
        return Db.SaveChanges() > 0;
    }

    //刪除
    public bool DeleteEntity(T entity)
    {
        Db.Entry<T>(entity).State = EntityState.Deleted;
        return Db.SaveChanges() > 0;
    }
    //批量添加
    public bool AddBatch(IList<T> arrObj)
    {
        Db.Set<T>().AddRange(arrObj);
        return Db.SaveChanges() > 0;
    }
    //批量更改
    public bool UpdateBatch(IList<T> arrObj)
    {
        foreach (var item in arrObj)
        {
            Db.Entry<T>(item).State = EntityState.Modified;
        }
        return Db.SaveChanges() > 0;
    }
    //批量刪除
    public bool DeleteBatch(IList<T> arrObj)
    {
        foreach (var item in arrObj)
        {
            Db.Entry<T>(item).State = EntityState.Deleted;
        }
        return Db.SaveChanges() > 0;
    }
    //分頁
    public IQueryable<T> LoadPageEntities<s>(int pageIndex, int pageSize, out int totalCount, System.Linq.Expressions.Expression<Func<T, bool>> whereLambda, System.Linq.Expressions.Expression<Func<T, s>> orderbyLambda, bool isAsc)
    {
        var temp = Db.Set<T>().Where<T>(whereLambda);
        totalCount = temp.Count();
        if (isAsc)//升序
        {
            temp = temp.OrderBy<T, s>(orderbyLambda).Skip<T>((pageIndex - 1) * pageSize).Take<T>(pageSize);
        }
        else
        {
            temp = temp.OrderByDescending<T, s>(orderbyLambda).Skip<T>((pageIndex - 1) * pageSize).Take<T>(pageSize);
        }
        return temp;
    }
}

實際使用

BaseDB<Student> baseDB = new BaseDB<Student>();
baseDB.AddEntity(new Student {
    StudentId = Guid.NewGuid().ToString(),
    Name = "小紅"
});