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Question

我準備一個SQL查詢來獲取一個簡單的論壇的最新話題，我有以下規定：

CREATE TABLE IF NOT EXISTS `f_categoria` (
    `id_categoria` int(4) NOT NULL, 
    `name` varchar(20) NOT NULL, 
    `desc` varchar(50) NOT NULL, 
    `id_foro` int(3) NOT NULL, 
    `estado` int(1) NOT NULL, 
    `visibilidad` int(2) NOT NULL, 
    PRIMARY KEY (`id_categoria`), 
    KEY `id_categoria` (`id_categoria`), 
    KEY `id_foro` (`id_foro`) 
) ENGINE=InnoDB DEFAULT CHARSET=utf8; 



INSERT INTO `f_categoria` (`id_categoria`, `name`, `desc`, `id_foro`, `estado`, `visibilidad`) VALUES 
(1, 'Programacion', 'Programacion', 1, 1, 1), 
(2, 'Modelado', 'Modeladoen 3d', 1, 1, 1); 

-- -------------------------------------------------------- 

CREATE TABLE IF NOT EXISTS `f_comentario` (
    `id_comentario` bigint(20) NOT NULL AUTO_INCREMENT, 
    `id_post` bigint(20) NOT NULL, 
    `id_user` bigint(20) NOT NULL, 
    `contenido` longtext NOT NULL, 
    `number` int(4) NOT NULL, 
    `fecha` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP, 
    PRIMARY KEY (`id_comentario`), 
    KEY `id_post` (`id_post`), 
    KEY `id_user` (`id_user`), 
) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=4 ; 



INSERT INTO `f_comentario` (`id_comentario`, `id_post`, `id_user`, `contenido`, `number`, `fecha`) VALUES 
(1, 1, 1, 'Este es el primer comentario', 1, '2013-07-30 23:12:53'), 
(2, 1, 1, 'Este es el comentario 2', 2, '2013-07-30 23:25:12'), 
(3, 2, 1, 'cOMENTARIO EN EL POST2', 1, '2013-07-30 23:53:44'); 

-- -------------------------------------------------------- 



CREATE TABLE IF NOT EXISTS `f_foro` (
    `id_foro` int(5) NOT NULL, 
    `name` varchar(15) NOT NULL, 
    `desc` varchar(50) NOT NULL, 
    `visibilidad` int(2) NOT NULL, 
    PRIMARY KEY (`id_foro`) 
) ENGINE=InnoDB DEFAULT CHARSET=utf8; 



INSERT INTO `f_foro` (`id_foro`, `name`, `desc`, `visibilidad`) VALUES 
(1, 'Prueba', 'Foro de prueba', 1); 

-- -------------------------------------------------------- 


CREATE TABLE IF NOT EXISTS `f_post` (
    `id_post` bigint(20) NOT NULL AUTO_INCREMENT, 
    `id_user` bigint(20) NOT NULL, 
    `titulo` varchar(50) NOT NULL, 
    `contenido` longtext NOT NULL, 
    `fecha` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP, 
    `estado` int(1) NOT NULL, 
    `id_categoria` int(4) NOT NULL, 
    PRIMARY KEY (`id_post`), 
    KEY `id_user` (`id_user`), 
    KEY `id_categoria` (`id_categoria`) 
) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=4 ; 



INSERT INTO `f_post` (`id_post`, `id_user`, `titulo`, `contenido`, `fecha`, `estado`, `id_categoria`) VALUES 
(1, 1, '¡Hola!', 'mensaje de prueba', '2013-07-30 23:12:05', 1, 1), 
(2, 1, 'post 2', 'es el post2', '2013-07-30 23:27:25', 1, 2), 
(3, 1, 'post3', 'el post3', '2013-07-31 00:04:52', 1, 1); 

-- -------------------------------------------------------- 



CREATE TABLE IF NOT EXISTS `f_user` (
    `id_user` bigint(20) NOT NULL AUTO_INCREMENT, 
    `name` varchar(15) NOT NULL, 
    `mail` varchar(50) NOT NULL, 
    `fecha` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP, 
    PRIMARY KEY (`id_user`), 
    UNIQUE KEY `name` (`name`,`mail`) 
) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=2 ; 

-- 
-- Volcado de datos para la tabla `f_user` 
-- 

INSERT INTO `f_user` (`id_user`, `name`, `mail`, `fecha`) VALUES 
(1, 'tulipo', 'f673150@rmqkr.net', '2013-07-30 23:07:36'); 




ALTER TABLE `f_categoria` 
    ADD CONSTRAINT `f_categoria_ibfk_1` FOREIGN KEY (`id_foro`) REFERENCES `f_foro` (`id_foro`); 


ALTER TABLE `f_comentario` 
    ADD CONSTRAINT `f_comentario_ibfk_2` FOREIGN KEY (`id_user`) REFERENCES `f_user` (`id_user`), 
    ADD CONSTRAINT `f_comentario_ibfk_1` FOREIGN KEY (`id_post`) REFERENCES `f_post` (`id_post`); 


ALTER TABLE `f_post` 
    ADD CONSTRAINT `f_post_ibfk_2` FOREIGN KEY (`id_categoria`) REFERENCES `f_categoria` (`id_categoria`), 
    ADD CONSTRAINT `f_post_ibfk_1` FOREIGN KEY (`id_user`) REFERENCES `f_user` (`id_user`); 

我怎樣才能使查詢檢索的最新訊息，但考慮到最後的意見？

這給了我最新的評論

select id_post,id_user,contenido,fecha from f_comentario group by id_post order by fecha DESC 

而且與過去後，

select id_post,id_user,contenido,fecha from f_post order by fecha DESC 

我不得不加入這兩個查詢，然後在最近10個id_post組他們（日期）...

有人給我一隻手？謝謝，並問候

Answer 1

糾正我，如果我誤解了你，但你要找的是最新的id_post，id_user，contenido，評論表的基礎上最後一次評論時，而不是當本身的時間被做了？

select TOP 10 f_com.id_post, f_com.id_user, f_pos.contenido, f_com.contenido, f_com.fecha 
from f_comentario f_com 
inner join f_post f_pos 
on f_pos.id_post = f_com.id_post 
order by fecha DESC 

這會給你存儲在f_comentario表內的值。 我認爲這是你想要的。 這是有點難以理解你想做什麼，因爲我不明白表名等 我希望這可以幫助

p.s.再次，您可以使用類似的連接來獲取用戶名，而不是用戶名和標題，而不是用戶標識，而不是用戶標識...