帮助复杂的加盟条件

Question

我有以下mysql表架构：

SET SQL_MODE="NO_AUTO_VALUE_ON_ZERO";

--
-- Database: `network`
--

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

--
-- Table structure for table `contexts`
--

CREATE TABLE IF NOT EXISTS `contexts` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `keyword` varchar(255) NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=MyISAM  DEFAULT CHARSET=latin1 AUTO_INCREMENT=4 ;

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

--
-- Table structure for table `neurons`
--

CREATE TABLE IF NOT EXISTS `neurons` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(255) NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=MyISAM  DEFAULT CHARSET=latin1 AUTO_INCREMENT=5 ;

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

--
-- Table structure for table `synapses`
--

CREATE TABLE IF NOT EXISTS `synapses` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `n1_id` int(11) NOT NULL,
  `n2_id` int(11) NOT NULL,
  `context_id` int(11) NOT NULL,
  `strength` double NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=MyISAM  DEFAULT CHARSET=latin1 AUTO_INCREMENT=6 ;

我可以编写哪种SQL来获取与指定上下文关联的所有神经元，以及与每个神经元关联的突触的强度列的总和？

我正在使用以下查询，该查询返回与一个神经元相关的突触强度的总和。 我需要获取所有神经元的信息：

/* This query finds how strongly the neuron with id 1 is connected to the context with keyword ice cream*/

SELECT SUM(strength) AS Strength FROM
synapses
JOIN contexts AS Context ON synapses.context_id = Context.id
JOIN neurons AS Neuron ON Neuron.id = synapses.n1_id OR Neuron.id = synapses.n2_id
WHERE Neuron.id = 1 AND Context.keyword = 'ice cream'

例如，该查询返回一行，其中“强度”为2。理想情况下，我可以为Neurons.id保留一列，为Neurons.name保留一列，为SUM（synapses.strength）保留一列，为每个不同的神经元保留一条记录。

Answer 1

这是您想要的吗？

SELECT contexts.keyword, neurons.id, neurons.name, SUM(synapses.strength)
FROM neurons
INNER JOIN synapses ON neurons.id = synapses.n1_id OR neurons.id = synapses.n2_id
INNER JOIN contexts ON synapses.context_id = contexts.id
GROUP BY contexts.keyword, neurons.id, neurons.name

Answer 2

采用：

   SELECT DISTINCT 
          n.*,
          COALESCE(x.strength, 0) AS strength
     FROM NEURONS n
     JOIN SYNAPSES s ON n.id IN (s.n1_id, s.n2_id)
     JOIN CONTEXTS c ON c.id = s.context_id
LEFT JOIN (SELECT c.id AS c_id,
                  n.id AS n_id,
                  SUM(strength) AS Strength 
             FROM SYNAPSES s
             JOIN CONTEXTS c ON c.id = s.context_id
             JOIN NEURONS n ON n.id IN (s.n1_id, s.n2_id)
         GROUP BY c.id, n.id) x ON x.c_id = c.id
                               AND x.n_id = n.id