Question

我有几个查询我想合并到1个查询中，我不确定正确的加入是什么。

此查询获取与pid匹配的所有弧：

var arcs = db.Query("SELECT arc FROM comics WHERE `publisher`=" + pid + " GROUP BY arc").ToList();

此查询从arcs表中获取弧的标题：

var ar = db.QuerySingle("SELECT title FROM arcs WHERE id=" + arc.arc);

此查询用于获取与arc.arc和pid匹配的总问题：

var issues = db.Query("SELECT id FROM comics WHERE arc=" + arc.arc + " AND publisher=" + pid);

整个代码：

@{
    var pid = Request["pid"];

    var db = Database.Open("quickly");
    var publisher = db.QuerySingle("SELECT * FROM publishers WHERE id=@0",  pid);

    Page.Title = publisher.name + " @";

    var arcs = db.Query("SELECT arc FROM comics WHERE `publisher`=" + pid + " GROUP BY arc").ToList();
}

<div class="post">
    <div class="post-bgtop">
        <div class="post-bgbtm">
            <h2 class="title">@publisher.name</h2>
            <div class="entry">
                <p>
                    <table width="100%" border="0">
                        <thead>
                            <tr>
                                <th align="left">Title</th>
                                <th>Issues</th>
                            </tr>
                        </thead>  
                        <tbody>
                            @foreach (var arc in arcs) {
                                var ar = db.QuerySingle("SELECT title FROM arcs WHERE id=" + arc.arc);
                                var issues = db.Query("SELECT id FROM comics WHERE arc=" + arc.arc + " AND publisher=" + pid);
                            <tr>
                                <td><a href="@Href("~/Comics/Arcs?aid=" + arc.arc)">@ar.title</a></td>
                                <td align="center">@issues.Count</td>
                            </tr>
                            }
                        </tbody>     
                    </table>
                </p>
            </div>
        </div>
    </div>
</div>

表格结构：

CREATE TABLE IF NOT EXISTS `arcs` (
  `id` int(255) NOT NULL AUTO_INCREMENT,
  `title` varchar(255) NOT NULL,
  `plot` longtext NOT NULL,
  `added` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
  PRIMARY KEY (`id`),
  UNIQUE KEY `title` (`title`)
) ENGINE=InnoDB  DEFAULT CHARSET=latin1;

CREATE TABLE IF NOT EXISTS `comics` (
  `id` varchar(255) NOT NULL,
  `arc` int(255) NOT NULL,
  `title` varchar(255) NOT NULL,
  `issue` decimal(5,1) DEFAULT NULL,
  `price` decimal(10,2) NOT NULL,
  `plot` longtext NOT NULL,
  `publisher` int(255) NOT NULL,
  `isbn` varchar(255) NOT NULL,
  `published` date NOT NULL,
  `cover` varchar(255) NOT NULL DEFAULT './images/nopic.jpg',
  `added` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
  `views` int(255) NOT NULL DEFAULT '0',
  `active` int(1) NOT NULL DEFAULT '0',
  `owned` int(1) NOT NULL DEFAULT '0',
  PRIMARY KEY (`id`),
  UNIQUE KEY `arc` (`arc`,`title`,`issue`,`publisher`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

CREATE TABLE IF NOT EXISTS `publishers` (
  `id` int(255) NOT NULL AUTO_INCREMENT,
  `name` varchar(255) NOT NULL,
  `plot` longtext NOT NULL,
  PRIMARY KEY (`id`),
  UNIQUE KEY `name` (`name`)
) ENGINE=InnoDB  DEFAULT CHARSET=latin1;

Answer 1

您必须向我们提供有关表格结构的更多信息。

我的第一种方法是这样的......

Select 
cs.arc as 'Arc', 
arcs.title as 'Arc_Title', 
id as 'Issues'
from 
Comics cs 
left join Arcs arcs on cs.arc = arcs.id
left join Comics cs2 on cs.arc = cs2.arc and publisher = @pid

但我真的不知道，因为我在猜表格结构

修改...

据我所知，一个弧可以出现在多个漫画中。而且你需要不同的弧线以及它们重复的次数。所以我认为这会奏效：

Select t1.arc as 'Arc_ID', t1.title as 'Arc_Title', count(t1.arc) as 'issues' from ( Select c.id, c.arc, a.title from comics c left join arcs a on c.arc = a.id where c.publisher = 1) as t1 group by t1.arc, t1.title

这是一个例子.. http://sqlfiddle.com/#!2/a9fda/8/0

合并3个SQL查询，什么是正确的连接？

1 个答案: