我正在尝试创建数据库访问层。我正在寻找一些关于最佳实践的课程/建议的改进。如果有人能够向我指出有关如何进行此项工作/需要考虑的事项的文档，将会很有帮助。我已经看过使用实体框架，但它似乎不适用，但是，我真的应该转向EF吗？ ADO.NET是一种过时的方式吗？
public static IDbCommand GetCommandObject(string Connstring)
{
IDbConnection conn = new SqlConnection(Connstring);
return new SqlCommand { Connection = (SqlConnection)conn };
}
public static void AddParameter(ref IDbCommand cmd, string Name, object value, DbType ParamType)
{
IDbDataParameter Param = cmd.CreateParameter();
Param.DbType = ParamType;
Param.ParameterName = (Name.StartsWith("@")) ? "" : "@"; //@ character for MS SQL database
Param.Value = value;
cmd.Parameters.Add(Param);
}
public static Int32 ExecuteNonQuery(string SQL, IDbCommand cmd = null)
{
Boolean CommitTrans = true;
Boolean CloseConn = true;
SqlTransaction Trans = null;
try
{
//IF Required - create command object if required
if (cmd == null) { cmd = DB.GetCommandObject(""); }
//Add the commandtext
cmd.CommandText = SQL;
if (cmd.Connection == null) { throw new Exception("No connection set"); }
//IF REQUIRED - open the connection
if (cmd.Connection.State == ConnectionState.Closed)
{
cmd.Connection.Open();
}
else
{
CloseConn = false;
}
if (cmd.Transaction != null)
{
//We have already been passed a Transaction so dont close it
CommitTrans = false;
}
else
{
//Create and open a new transaction
Trans = (SqlTransaction)cmd.Connection.BeginTransaction();
cmd.Transaction = Trans;
}
Int32 rtn = cmd.ExecuteNonQuery();
if (CommitTrans == true) { Trans.Commit(); }
return rtn;
}
catch (Exception e)
{
if (CommitTrans == true) { Trans.Rollback(); }
throw new Exception();
}
finally
{
if (CloseConn == true)
{
cmd.Connection.Close();
cmd = null;
}
}
}
public static object ExecuteScalar(string SQL, IDbCommand cmd, Boolean NeedsTransaction = true)
{
Boolean CommitTrans = true;
Boolean CloseConn = true;
SqlTransaction Trans = null;
try
{
//IF Required - create command object if required
if (cmd == null) { cmd = DB.GetCommandObject(""); }
//Add the commandtext
cmd.CommandText = SQL;
//IF REQUIRED - create default Connection to CourseBuilder DB
if (cmd.Connection == null) { throw new Exception("No Connection Object"); }
//IF REQUIRED - open the connection
if (cmd.Connection.State == ConnectionState.Closed)
{
cmd.Connection.Open();
}
else
{
CloseConn = false;
}
if (NeedsTransaction == true)
{
if (cmd.Transaction != null)
{
//We have already been passed a Transaction so dont close it
CommitTrans = false;
}
else
{
//Create and open a new transaction
Trans = (SqlTransaction)cmd.Connection.BeginTransaction();
cmd.Transaction = Trans;
}
}
Object rtn = cmd.ExecuteScalar();
if (NeedsTransaction == true && CommitTrans == true) { Trans.Commit(); }
return rtn;
}
catch
{
if (NeedsTransaction == true && Trans != null) { Trans.Rollback(); }
throw new Exception();
}
finally
{
if (CloseConn == true) { cmd.Connection.Close(); cmd = null; }
}
}
public static DataRow GetDataRow(string SQL, IDbCommand cmd = null, Boolean ErrorOnEmpty = true)
{
var dt = FillDatatable(SQL, ref cmd);
if (dt.Rows.Count > 0)
{
return dt.Rows[0];
}
else
{
if (ErrorOnEmpty == true) { throw new Exception(nameof(GetDataRow) + " returned no rows."); }
return null;
}
}
public static DataTable FillDatatable(string SQL, ref IDbCommand cmd)
{
string newline = System.Environment.NewLine;
var DT = new DataTable();
Boolean LeaveConOpen = false;
try
{
//Add the commandtext
cmd.CommandText = SQL;
//IF REQUIRED - create default Connection to CourseBuilder DB
if (cmd?.Connection == null) { throw new Exception("No Connection Object"); }
if (cmd.Connection.State != ConnectionState.Open)
{
cmd.Connection.Open();
LeaveConOpen = false;
}
else
{
LeaveConOpen = true;
}
var DA = new SqlDataAdapter((SqlCommand)cmd);
DA.Fill(DT);
}
catch (Exception ex)
{
var sbErr = new StringBuilder();
sbErr.AppendLine("Parameters (type defaults to varchar(max)):" + newline);
foreach (SqlParameter p in cmd.Parameters)
{
string s = "";
sbErr.AppendLine("declare " + p.ParameterName + " varchar(max) = '" + (p.Value == DBNull.Value ? "Null" : p.Value + "'; ") + newline);
}
sbErr.AppendLine(newline + SQL + newline);
throw new Exception("Failed to FillDataTable:" + newline + newline + sbErr.ToString(), ex);
}
finally
{
if (LeaveConOpen == false) { cmd.Connection.Close(); }
}
return DT;
}
public static T CheckNull<T>(T value, T DefaultValue)
{
if (value == null || value is System.DBNull)
{
return DefaultValue;
}
else
{
return value;
}
}
答案 0 :(得分：0)
创建DAL时要记住几件事情
替代方案是使用像Dapper这样的东西。
