ado.net

　　数据库得操作无非是增删查改，增删改由ExecuteNonQuery实现，查由SqlDataReader实现，dataset主要用于绑定表格数据。

SqlDataReader

public static SqlDataReader ExecuteReader(SqlConnection connection, SqlTransaction transaction, CommandType commandType, string commandText, SqlParameter[] commandParameters, SqlConnectionOwnership connectionOwnership)
{
SqlCommand sqlCommand = new SqlCommand();
SqlDataReader result;
try
{
connection.Open();
PrepareCommand(sqlCommand, connection, transaction, commandType, commandText,
commandParameters);
SqlDataReader sqlDataReader;
if (connectionOwnership == SqlConnectionOwnership.External)
{
sqlDataReader = sqlCommand.ExecuteReader();
}
else
{
sqlDataReader = sqlCommand.ExecuteReader(CommandBehavior.CloseConnection);
}
bool flag2 = true;
foreach (SqlParameter sqlParameter in sqlCommand.Parameters)
{
if (sqlParameter.Direction != ParameterDirection.Input)
{
flag2 = false;
}
}
if (flag2)
{
sqlCommand.Parameters.Clear();
}
result = sqlDataReader;
}
catch(Exception e)
{
throw e;
}
finally
{

}
return result;
}

SqlParameter

public static void AttachParameters(SqlCommand command, SqlParameter[] commandParameters)
{
if (command == null)
{
throw new ArgumentNullException("command");
}
if (commandParameters != null)
{
for (int i = 0; i < commandParameters.Length; i++)
{
SqlParameter sqlParameter = commandParameters[i];
if (sqlParameter != null)
{
if ((sqlParameter.Direction == ParameterDirection.InputOutput ||
sqlParameter.Direction == ParameterDirection.Input) && sqlParameter.Value == null)
{
sqlParameter.Value = DBNull.Value;
}
command.Parameters.Add(sqlParameter);
}
}
}
}

public static void PrepareCommand(SqlCommand command, SqlConnection connection, SqlTransaction transaction,
CommandType commandType, string commandText, SqlParameter[] commandParameters)
{
if (command == null)
{
throw new ArgumentNullException("command");
}
if (commandText == null || commandText.Length == 0)
{
throw new ArgumentNullException("commandText");
}
if (connection.State != ConnectionState.Open)
{
connection.Open();
}
command.Connection = connection;
command.CommandText = commandText;
if (transaction != null)
{
if (transaction.Connection == null)
{
throw new ArgumentException("打开状态的事务允许数据操作回滚或者提交。", "事务");
}
command.Transaction = transaction;
}
command.CommandType = commandType;
if (commandParameters != null)
{
AttachParameters(command, commandParameters);
}
}

DataSet

public static DataSet ExecuteDataset(SqlConnection connection, CommandType commandType,
string commandText, params SqlParameter[] commandParameters)
{
if (connection == null)
{
throw new ArgumentNullException("connection");
}
SqlCommand sqlCommand = new SqlCommand();

PrepareCommand(sqlCommand, connection, null, commandType, commandText, commandParameters);
DataSet result;
using (SqlDataAdapter sqlDataAdapter = new SqlDataAdapter(sqlCommand))
{
DataSet dataSet = new DataSet();
sqlDataAdapter.Fill(dataSet);
sqlCommand.Parameters.Clear();

result = dataSet;
}
return result;
}

源码

　　https://git.oschina.net/zkzk945/AdoNetSqlServer.git 源码实现了数据库得增删查改。