/// <summary>
/// 查询数据库返回结果。
/// </summary>
/// <param name="converter">对象转换器。</param>
/// <returns>返回数据列表。</returns>
public TValue FirstOrDefault <TValue>(Func <DbDataReader, TValue> converter)
{
Size = 1;
if (_fields.Count == 0)
{
_fields.Add($"{GetAlias(typeof(TModel))}.*");
}
using (var reader = _db.ExecuteReader(_sqlGenerator.Query(this).ToString()))
{
if (reader.Read())
{
return(converter(reader));
}
}
return(default);
/// <summary> /// 查询实例对象。 /// </summary> /// <param name="commandText">SQL字符串。</param> /// <param name="parameters">参数实例对象。</param> /// <param name="commandType">命令类型。</param> /// <returns>返回数据库读取实例接口。</returns> public DbDataReader ExecuteReader(string commandText, object parameters = null, CommandType commandType = CommandType.Text) => _executor.ExecuteReader(commandText, parameters, commandType);
