三层架构入门级（附数据库脚本）

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Data;

namespace BLL
{
    public  class department
    {
        IDAL.IDepartment dDep = DalFactory.DataAcess.CreateDepartment（）;
        public bool insert（Model.Department mDep）
        {
            return dDep.insert（mDep）;
        }
        public bool update（Model.Department mDep string oldDepId）
        {
            return dDep.update（mDep oldDepId）;
        }
        public bool delete（string depId）
        {
            return dDep.delete（depId）;
        }
        public DataTable select（string strWhere）
        {
            return dDep.select（strWhere）;
        }
    }
}

 属性            大小     日期    时间   名称
----------- ---------  ---------- -----  ----
     目录           0  2019-09-23 14:15  Threelayer\
     目录           0  2019-09-24 12:46  Threelayer\BLL\
     目录           0  2019-09-07 13:33  Threelayer\BLL\bin\
     目录           0  2019-09-24 22:55  Threelayer\BLL\bin\Debug\
     文件        6144  2019-09-24 22:57  Threelayer\BLL\bin\Debug\BLL.dll
     文件       17920  2019-09-24 22:57  Threelayer\BLL\bin\Debug\BLL.pdb
     文件        5120  2019-09-23 15:04  Threelayer\BLL\bin\Debug\DalFactory.dll
     文件       13824  2019-09-23 15:04  Threelayer\BLL\bin\Debug\DalFactory.pdb
     文件        4608  2019-09-23 14:32  Threelayer\BLL\bin\Debug\IDAL.dll
     文件        7680  2019-09-23 14:32  Threelayer\BLL\bin\Debug\IDAL.pdb
     文件        4608  2019-09-23 14:32  Threelayer\BLL\bin\Debug\Model.dll
     文件        7680  2019-09-23 14:32  Threelayer\BLL\bin\Debug\Model.pdb
     目录           0  2019-09-07 13:33  Threelayer\BLL\bin\Release\
     文件        3077  2019-09-24 22:55  Threelayer\BLL\BLL.csproj
     文件         755  2019-09-24 22:57  Threelayer\BLL\department.cs
     目录           0  2019-09-07 13:32  Threelayer\BLL\obj\
     目录           0  2019-09-24 22:57  Threelayer\BLL\obj\Debug\
     文件         614  2019-09-24 22:55  Threelayer\BLL\obj\Debug\BLL.csproj.FileListAbsolute.txt
     文件       19638  2019-09-24 12:46  Threelayer\BLL\obj\Debug\BLL.csprojResolveAssemblyReference.cache
     文件        6144  2019-09-24 22:57  Threelayer\BLL\obj\Debug\BLL.dll
     文件       17920  2019-09-24 22:57  Threelayer\BLL\obj\Debug\BLL.pdb
     文件        6672  2019-09-24 22:54  Threelayer\BLL\obj\Debug\DesignTimeResolveAssemblyReferencesInput.cache
     文件           0  2019-09-07 13:32  Threelayer\BLL\obj\Debug\TemporaryGeneratedFile_036C0B5B-1481-4323-8D20-8F5ADCB23D92.cs
     文件           0  2019-09-07 13:32  Threelayer\BLL\obj\Debug\TemporaryGeneratedFile_5937a670-0e60-4077-877b-f7221da3dda1.cs
     文件           0  2019-09-07 13:32  Threelayer\BLL\obj\Debug\TemporaryGeneratedFile_E7A71F73-0F8D-4B9B-B56E-8E70B10BC5D3.cs
     目录           0  2019-09-07 13:32  Threelayer\BLL\obj\Debug\TempPE\
     目录           0  2019-09-07 13:32  Threelayer\BLL\Properties\
     文件        1326  2019-09-07 13:32  Threelayer\BLL\Properties\AssemblyInfo.cs
     目录           0  2019-09-24 12:46  Threelayer\BLL\Service References\
     文件        1676  2019-09-24 22:57  Threelayer\BLL\student.cs
     目录           0  2019-09-06 15:40  Threelayer\DAL\
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