/// <summary>
/// 쿼리를 실행하고 쿼리에서 반환된 결과 집합에서 첫 번째 행의 첫 번째 열을 반환합니다.
/// </summary>
/// <typeparam name="T">Generic object, 결과값 형타입</typeparam>
/// <param name="commandType">CommandType</param>
/// <param name="commandText">Transact-SQL statement, table name or stored procedure</param>
/// <param name="parameters">SP(저장프로시저)나 SQL 문 파라메터에 할당되는 object 배열</param>
/// <returns>T(Generic object) 타입 값</returns>
public T ExecuteScalar <T>(CommandType commandType, string commandText, params object[] parameters) where T : IConvertible
{
try
{
_command.CommandType = commandType;
_command.CommandText = commandText;
if (commandType == CommandType.Text && parameters != null)
{
ProcessParameters(_provider, _command, commandText, parameters);
}
_connection.Open();
var result = _command.ExecuteScalar();
return(GlobalConvert.ChangeType <T>(result));
}
catch (DbException dbEx)
{
if (_handleErrors)
{
_lstError = dbEx.Message;
}
else
{
throw dbEx; // CustomException DB, dbEx
}
}
catch (Exception ex)
{
if (_handleErrors)
{
_lstError = ex.Message;
}
else
{
throw ex; // CustomException System, ex
}
}
return(GlobalConvert.DefaultValue <T>());
}
protected T GetValue <T>(object key, T defaultValue) where T : IConvertible
{
return(GlobalConvert.ChangeType <T>(this[key], defaultValue));
}