Question

除了具体的例子，我几乎不知道如何提出这个问题，所以这里是：

我们有一个活动注册表，我希望匹配在过去5年中每年注册过4个活动之一的注册人。

我能想到这样做的唯一方法是使用冗长的子查询，但在性能方面它是绝对的狗：

<div class="layout-header">
  <h1></h1>
</div>
<div class="layout-middle">
  <div class="layout-left">
    <!-- start content -->
    <div class="panel">
      <header>panel header</header>
      <div class="select-list" id="select-list">
        <div class="select-list-item selected">0: bg</div>
        <div class="select-list-item selected">0: bg</div>
        <div class="select-list-item selected">0: bg</div>
        <div class="select-list-item selected">0: bg</div>
        <div class="select-list-item selected">0: bg</div>
        <div class="select-list-item selected">0: bg</div>
        <div class="select-list-item selected">0: bg</div>
        <div class="select-list-item selected">0: bg</div>
        <div class="select-list-item selected">0: bg</div>
        <div class="select-list-item selected">0: bg</div>
        <div class="select-list-item selected">0: bg</div>
        <div class="select-list-item selected">0: bg</div>
        <div class="select-list-item selected">0: bg</div>
        <div class="select-list-item selected">0: bg</div>
        <div class="select-list-item selected">0: bg</div>
        <div class="select-list-item selected">0: bg</div>
      </div>
      <footer></footer>
    </div>
    <div class="panel">
      <header>Entities</header>
      <div class="select-list" id="select-list">
        <div class="select-list-item selected">0: bg</div>
        <div class="select-list-item selected">0: bg</div>
        <div class="select-list-item selected">0: bg</div>
        <div class="select-list-item selected">0: bg</div>
        <div class="select-list-item selected">0: bg</div>
        <div class="select-list-item selected">0: bg</div>
        <div class="select-list-item selected">0: bg</div>
        <div class="select-list-item selected">0: bg</div>
        <div class="select-list-item selected">0: bg</div>
        <div class="select-list-item selected">0: bg</div>
        <div class="select-list-item selected">0: bg</div>
        <div class="select-list-item selected">0: bg</div>
        <div class="select-list-item selected">0: bg</div>
        <div class="select-list-item selected">0: bg</div>
        <div class="select-list-item selected">0: bg</div>
        <div class="select-list-item selected">0: bg</div>
      </div>
      <footer></footer>
    </div>
    <div class="panel">
      <header>Entities</header>
      <div class="select-list" id="select-list">
        <div class="select-list-item selected">0: bg</div>
        <div class="select-list-item selected">0: bg</div>
        <div class="select-list-item selected">0: bg</div>
        <div class="select-list-item selected">0: bg</div>
        <div class="select-list-item selected">0: bg</div>
        <div class="select-list-item selected">0: bg</div>
        <div class="select-list-item selected">0: bg</div>
        <div class="select-list-item selected">0: bg</div>
        <div class="select-list-item selected">0: bg</div>
        <div class="select-list-item selected">0: bg</div>
        <div class="select-list-item selected">0: bg</div>
        <div class="select-list-item selected">0: bg</div>
        <div class="select-list-item selected">0: bg</div>
        <div class="select-list-item selected">0: bg</div>
        <div class="select-list-item selected">0: bg</div>
        <div class="select-list-item selected">0: bg</div>
      </div>
      <footer></footer>
    </div>
    <!-- end content -->
  </div>
  <main class="layout-stage">
    <h2>stage</h2>
  </main>
  <aside class="layout-right">
    <h2>right</h2>

  </aside>
</div>
<div class="layout-footer">
  <h2>Footer</h2>
</div>

每年等等。就像我说的那样，不是很有说服力或效率很高。

有更简单的方法吗？

Answer 1

您可以使用GROUP BY执行HAVING，然后使用当前年度事件执行INTERSECT

SELECT FirstName, LastName, DOB
FROM RegTable
WHERE EventId IN (1,2,3,4)
AND EventYear IN (2011,2010,2009,2008,2007)
GROUP BY FirstName, LastName, DOB
HAVING COUNT(Distinct EventYear) = 5

INTERSECT

SELECT DISTINCT FirstName ,LastName ,DOB
FROM RegTable 
WHERE EventId IN (1,2,3,4) 
AND EventYear = 2012

以上查询与样本数据一起使用。 SQL Fiddle

Answer 2

我最好不明白这个问题，只是重写你的查询（假设它正在做你需要的）：

SELECT RT2011.FirstName, RT2011.LastName, RT2011.EmailAddress 
FROM 
  RegTable RT2011, 
  RegTable RT2012
WHERE RT2011.EventId IN (1,2,3,4)
  AND RT2012.EventId IN (1,2,3,4)
  AND RT2011.EventYear = 2011
  AND RT2012.EventYear = 2012
  AND RT2011.FirstName = RT2012.FirstName
  AND RT2011.LastName = RT2012.LastName
  AND RT2011.DOB = RT2012.DOB

T-SQL组由多年组成

2 个答案: